Question

5 years ago the sum of the ages of a mother and her daughter was 60 years also the difference of their ages 5 years from now will be 30 years find the present age of the daughter

Answer 1

Let the age of the mother = x, the daughter = y

(x - 5) + (y - 5) = 60
x + y - 10 = 60
x + y = 60 + 10
x + y = 70

(x + 5) - (y + 5) = 30
x + 5 - y - 5 = 30
x - y = 30

x + y = 70
x -  y = 30 -
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2y = 40
y = 40 : 2
y = 20

x + y = 70
x + 20 = 70
x = 70 - 20
x = 50

The present age of the daughter is 20 years old