37 1 2 = 75 2

Required number =   75 2 1 8 = 75 x 4 = 300

Let the number  of 20 paise coins be x. Then the no of 25 paise coins = (324 - x).

0.20 * (x) + 0.25 (324 - x) = 71 => x = 200..

Apply  a 3 + b 3 + c 3 - 3 a b c a 2 + b 2 + c 2 - a b - b c - c a = a + b + c

Hence the answer is  1.5 + 4.7 + 3.8 = 10.

Let the score be x. Then the highest score = 3x/11.

Reminder = (x - 3x/11) = 8x/11 .Next the highest score = 3/11 of 8x/11 = 24x/121.

3x/11 - 24x/11 = 9 <=> 33x - 24x = 9*121 <=> x= 121..

Given  9261 3 x 62742241 = ? + 89

Using unit digit method,

On LHS,

1 x 1 x 1 = 1

sqrt of last digit 1 => it must end with either 9 or 1

so now

1 x 1 = 1

1 x 9 = 9

On RHS,

? + 89

=> ? = ...1 - 89 = last digit is 11- 9 = 2

or

=> ? = ...9 - 89 = last digit is 9 - 9 = 0

Here in the options last digit 2 is option C.

$$\begin{gathered} 112 × 5 4 \\ 112 × 10 2 4 \\ = 112 × 10000 2 4 \\ = 1120000 / 16 \end{gathered}$$

= 70,000.

Let the number of buffaoes be x and number of ducks be y.

Then 4x + 2y = 2(x + y) + 24  

=> 2x = 24

=> x = 12.

$$\begin{gathered} 1 3 x ? + 4 7 x 11 4 x 539 = 31 100 x 2000 \\ ? = 378 x 3 \\ ? = 1134 \end{gathered}$$

$$\begin{gathered} ? 2 = 2 × 7 8 - 21 + 8 + 49 - 14 8 \\ = 57 - 21 \\ = 36 \\ = > ? = ± 6 \end{gathered}$$

3/5 of  350 - 4/7 of 210 = 210 - 120 = 90.