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- Question
- If 3x + 7y = 75 and 5x - 5y = 25, what is the value of x + y?
Options- A. 14
- B. 15
- C. 16
- D. 17
- Correct Answer
- 17
Explanation3x + 7y = 75 ..(i)
5x - 5y = 25
? x - y = 5 ...(ii)
On multiplying Eq. (ii) by 7 and adding to Eq. (i), we get
3x + 7y = 75
7x - 7y = 35
------------------
10x = 110
x = 11
? Putting the value of x in Eq. (ii), we get
11 - y = 5
? y = 6
? x + y = 6 + 11 = 17 - 1. If 2x + 3y = 29 and y = x + 3, what is the value of x?
Options- A. 4
- B. 5
- C. 6
- D. 7 Discuss
- 2. The cost of 5 pens and 8 pencils is ?31.What would be the cost of 15 pens and 24 pencils?
Options- A. ?93
- B. ?99
- C. ?96
- D. Cannot be determined Discuss
- 3. Cost of 36 pens and 42 pencils is ? 460/- . What is the cost of 18 pens and 21 pencils?
Options- A. ?230/-
- B. ?203/-
- C. ?302/-
- D. ?320/- Discuss
- 4. When 20 is subtracted from a number , it reduces to seven- twelve of the number. What is the sum of the digit of the number?
Options- A. 16
- B. 44
- C. 48
- D. 12 Discuss
- 5. The sum of three numbers is 300. If the ratio between first and second be 5:9 and that between second and third be 9:11, then second number is
Options- A. 12
- B. 60
- C. 108
- D. 132 Discuss
- 6. If x + y - 7 = 0 and 3x + y - 13 = 0, then what is 4x 2 + y 2 + 4xy equal to?
Options- A. 75
- B. 85
- C. 91
- D. 100 Discuss
- 7. if 3 x + y = 81 and 81 x - y = 3, then what is the value of x?
Options- A. 17/16
- B. 17/8
- C. 17/4
- D. 15/4 Discuss
- 8. solve 6x + 3y = 7xy and 3x + 9y = 11xy.
Options- A. x=1, y=3/2
- B. x=-1, y = 3/2
- C. x=3/2, y=1/2
- D. x=1, y= -3/2 Discuss
- 9. Deepak has some hens and some goats. If the total number of animal heads is 90 and the total number of animal feet is 248, what is the total number of goats Deepak has?
Options- A. 32
- B. 36
- C. 34
- D. Cannot be determined Discuss
- 10. The sum of the two digits is 15 and the difference between them is 3. What is the product of the digits?
Options- A. 56
- B. 63
- C. 42
- D. Cannot be determined Discuss
Linear Equation problems
Search Results
Correct Answer: 4
Explanation:
2x + 3y = 29 ...(i)
and y = x + 3 ...(ii)
Putting the value of y from Eq. (ii) to Eq. (i), we get
2x + 3y = 29
2x + 3(x + 3) = 29
2x + 3x + 9 = 29
? 5x = 20
? x = 4
Correct Answer: ?93
Explanation:
Cost of 5 pens + 8 pencils = ?31
On multiplying by 3
15 pens + 24 pencils = 3 x 31 =
?15 pens + 24 pencils = 93
Correct Answer: ?230/-
Explanation:
Let us assume 1 pen cost be ? x and 1 pencil cost be ? y.
According to question,
The Cost of 36 pens and 42 pencils is 460.
36x + 42y = 460 ...................(1)
then the cost of 18 pens and 21 pencils = 18x + 21y.
Now divide the Equation (1) by 2. We will get,
18x + 21y = 230
So the Cost of 18 pens and 21 pencils = 18x + 21y = 230
Correct Answer: 12
Explanation:
Let the number be x.
According to question,
x - 20 = 7x/12
? x - 7x/12 = 20
? (12x - 7x)/12 = 20
? 5x/12 = 20
? x = 20 x 12/5
? x = 4 x 12
? x = 48
Sum of the digits of 48 = 4 + 8 = 12
Correct Answer: 108
Explanation:
Let us assume the ratio factor is x.
Then the three numbers be 5x , 9x and 11x respectively.
Then according to question,
5x + 9x + 11x = 300
? 25x = 300
? x = 12
So, the second number is 9x = 9 x 12 =108
Correct Answer: 100
Explanation:
we have, x + y - 7 = 0
? x + y = 7 ...(i)
and 3x + y - 13 = 0
? 3x + y = 13 ..(ii)
By subtracting Eq. (i) from Eq. (ii), we get
3x + y = 13
x + y = 7
----------------------
2x = 6 ...(ii)
? x = 3
On putting the value of x in Eq. (i), we get
3 + y = 7
? y = 4
Now, 4x2 + y2 + 4xy
= 4 x (3)2 + (4)2 + 4 x 3 x 4
= 4 x 9 + 16 + 48
= 36 + 16 + 48 = 100
Correct Answer: 17/8
Explanation:
Given, 3x + y = 81
? 3x + y = 34
? x + y = 4 ...(i)
and 81x - y = 3 or (34)x - y = 3
? x - y = 1/4
On solving the Eqs. (i) and (ii), we get
2x = 17/4 ? x = 17/8
Correct Answer: x=1, y=3/2
Explanation:
Given equation are 6x + 3y = 7xy
? (6/y) + (3/x) = 7 .....(i)
And 3x + 9y = 11xy
? (3/y) + (9/x) = 11 .....(ii)
On multiplying Eq. (ii) by 2 and subtracting from Eq. (i), we get
(6/y) + (3/x) = 7
(6/y) + (18/x) = 22
-------------------------
- 15/x = - 15
? x = 1
On putting this value in Eq. (i), we get
(6/y) + 3 = 7
? 6/y = 4
? y = 6/4 = 3/2
Correct Answer: 34
Explanation:
Let hens = H, goats = G
According to the question,
H + G = 90 ...(i)
2H + 4G = 248 ...(ii)
On multiplying Eq. (i) by 2 and subtracting from Eq. (ii) , we get
2H + 2G = 180
2H + 4G = 248
-------------------
-2G = -68
? G = 34
Correct Answer:
Explanation:
Let the number be x and y.
Then, according to the question,
x + y = 15 ...(1)
x - y = 3 ...(ii)
on adding Eqs. (i) and (ii), we get
2x = 18
? x = 9
On putting the value of in Eq. (i), we get
y = 6
? Product = xy = 54
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