Question

The ratio of Mrs Lee's age to her son's age now is 4 : 1

Answer 1

The ratio of Mrs Lee's age to her son's age now is 4 : 1

5 years later, the ratio of Mrs Lee's age to her son's age will become 3 : 1

How old is Mrs Lee now?

Answer: Let Mrs Lee's age and her son's age now be 4x and x respectively.

Mrs Lee's age after 5 years = 4x + 5

Her son's age after  years = x + 5

We know that the ratio of Mrs Lee's age to her son's age after 5 years will be 3:1. Therefore, we have:

$\frac{4x+5}{x+5} =\frac{3}{1}$

$4x +5 =3x +15$

$4x -3x = 15-5$

$x=10$

We have son's current age = 10 years

Therefore, Mrs Lee's is $4 \times 10 =40$ years old now