Kim;s father is 7 times her age. In 20 years time he will be twice her age. How old are they now?

Question

I need help and working out with alegbra

Answer 1

Let f = father's age

Let k = Kim's age

 

Father is seven times Kim's age:

f = 7k    {equation 1}

 

In 20 years time he will be twice her age:

f + 20 = 2(k+20)

f + 20 = 2k + 40

f - 2k = 20   {equation 2}

 

Replace f with 7k in equation w and solve for k:

7k - 2k = 20

5k = 20

k = 4

 

f = 7k = 28

 

Kim is 4 years old, her father is 28