Sushma joins a job at 20 yrs. First 3 years salary is 10,000 p.a. Afterwards every year increment of 2,000 per year for 10 years. Then salary becomes constant till retirement. At retirement average salary is 25,000. (throughout career). At what age Sushma retires ?

Let the mother's age 2 years ago be 4x and daughter's age 2 years ago be be x.
? (4x + 8) - (x + 8) = 12
? 3x = 12
? x = 4
? Mother's present age = 4x + 2 = 18 years
and daughter's present age = x + 2 = 6 years
? Required ratio = 3 : 1

Let the present age of the son be x and that of the father be 4x years.
? (x - 5) + (4x - 5) = 60
? 5x = 70
? x = 14 years
? Father's present age = 4x = 56 years

Age of C < Age of A < Age of B

From question,
A = C + x ....(i)
B = A + x ....(ii)

From equation (i) and (ii)
A - B = C - A
? 2A = B + C
? A = (B + C) / 2

Given that sum of the ages of B and C is 40 years.
So, A = (B + C) / 2 = 40/2 = 20 Years

Let the present age of A is x and present age of B is y.
Therefore, x + y = 63 ....(i)
Difference of their ages is = (x - y) years.

When A was as old as B then, A's age was 'y; years and B's age was [y - (x - y)] = (2y - x) years.

Given that present age of A is twice the past age of B.
? x = 2(2y - x)
? 3x = 4y .....(ii)

From (i) and (ii)
x = 36 and y = 27

So the difference in age of A and B is 36 - 27 = 9 years.

Let the ages of Harish and Seema be x and y respectively.
According to the question,
xy = 240 ....(i)
2y - x = 4 ....(ii)
Solving equations (i) and (ii), we get
y = 12 years

Let the present age of Pradhan be P years and his father's age = Q years.

From 1st condition,
(P + 6) = (Q + 6 ) x 3/7
? 7P + 42 = 3Q + 18
? 7P - 3Q = -24 ...(i)

From 2nd condition
(P - 10) / (Q - 10) = 1/5
? 5P - 50 = Q - 10
? 5P - Q = 40 .....(ii)

Multiplying equation (ii) by 3 and subtracting from (i) we get
P = 18, Q = 50
So present age of Pradhan's father = 50 years.

Let the present age of Kunal be 3x year and the
present age of Ganesh = 5x years.

According to question ,
(5x + 4 ) - (3x + 4 ) = 12
? 2x = 12
? x = 6
? Present age of Kunal = 3x = 3 x 6 = 18 year

? Total age of 9 students and a teacher = 10 x 16 = 160 yr
Total age of first 4 students = 4 x 19 = 76 yr
and total age of last 5 students = 5 x 10 = 50 yr
? Age of teacher = 160 - 76 - 50 = 34 yr

Let the present ages of Maya and Chhaya are 6N and 5N yr. respectively.

According to the question, After 15 yr,
(6N + 15) / (5N + 15) = 9/8
? 48N + 120 = 45N + 135
? N = 5
Hence, present age of Maya = 5 x 6 = 30 yr

Let Arnav's age = k yr
Then, Palash's age = 3k yr
Acoording to the question, 3k + 7 = 2(k + 7)
? 3k + 7 = 2k + 14
? k = 7

? Age of Arnav after 14 yr = 7 + 14 = 21 yr
and Palash's present age = 21 yr

Hence, Palash's age is one time of Arnav's age .