Question

A man has two daughters, one three times as old as the other. The man is five times as old as his older daughter and in 5 years he will be five times as old as the younger. Find their present ages.

Answer 1

Let d_one = the oldest daughter

Let d_two = the younger daughter.

Let the father = dad.

d_one= 3*d_two . . . . . . . . . . (1)

dad = 5*d_one . . . . . . . . . . . (2)

dad + 5 = 5*(d_two + 5) . . . .(3)

Now you have to put all this information in a solvable form.

Put (1) into three.

5*d_one + 5 = 5*(d_two + 5) Put (1) into this equation

5*(3*d_two) + 5 = 5*(d_two + 5) Remove both sets of brackets.

15*d_two + 5 = 5*d_two + 25 subtract 5 from both sides.

15*d_two = 5*d_two + 20 Subtract 5*d_two

10*d_two = 20 Divide both sides by 10

d_two = 20/10

d_two = 2

d_one is current 2 *3 = 6

dad is 5*d_one = 5* 6 = 30

Summery

The youngest child is currently 2

the oldest one is currently 2*3 = 6

Dad is currently 30