Question

the ratio of a and b is 2:3. ten year later,their ages will be in the ratio of 4:5. what will be b's age after 5 year?​

Answer 1

20 years

Explanation:

The ratio of ages = 2 : 3 = 2x : 3x ( x is a multiplier )

After 10 years their ages will be

2x + 10 : 3x + 10 = 4 : 5

Express the ratio in fractional form

`(2x+10)/(3x+10)` =
`(4)/(5)` ( cross- multiply )

4(3x + 10) = 5(2x + 10) ← distribute parenthesis on both sides )

12x + 40 = 10x + 50 ( subtract 10x from both sides )

2x + 40 = 50 ( subtract 40 from both sides )

2x = 10 ( divide both sides by 2 )

x = 5

Thus b's age = 3x = 3 × 5 = 15

So in 5 years b will be 15 + 5 = 20

Answer 2

soln,

let the given ratio be 2x and 3x.

the ratio after 10 yrs will be (2x+10) & (3x+10)

according to the question,

2x+10/3x+10 = 4/5

now do cross multiply & you will get your answer