Question

4. The ages of A and B are in the ratio 5 : 7.
Four years from now the ratio of their ages
will be 3 : 4. Then the present age of B is:
A. 20 years
B. 28 years
C. 15 years
D. 21 years
​

Answer 1

Answer:

A. 20 years will be the age of B

Answer 2

Answer:

Here's your answer

Let the present ages of A and B be 5x and 7x

ACCORDING TO QUESTION...

$\frac{5x + </strong><strong>4</strong><strong>}{7x + </strong><strong>4</strong><strong>} = \frac{3}{4} \\ \\ 4 (5x + </strong><strong>4</strong><strong>) = 3(7x + </strong><strong>4</strong><strong>) \\ \\ 20x + </strong><strong>1</strong><strong>6</strong><strong> = 21x + 1</strong><strong>2</strong><strong>\\ \\ 20x - 21x = 1</strong><strong>2</strong><strong> - </strong><strong>1</strong><strong>6</strong><strong> \\ \\ - x = - </strong><strong>4</strong><strong> \\ \\ x = </strong><strong>4</strong><strong>$

$x = </strong><strong>4</strong><strong>$

SO THE PRESENT AGE OF B will be 7x =7×4= 28years...

So the correct answer is (b) 28...

Hope it helps ✌.....