Question

Martha is five years older than her sister. Martha’s father is three times Martha’s age, whole her mother is eight times the age of her sister. If the total of the ages of each of these four family members is 72, how old is Martha?

Answer 1

Martha's sister: x years old

Martha: x+5

Her father: 3(x+5)

Her mother: 8x

Total: 72

x+5+x+3(x+5)+8x=72

x+5+x+3x+15+8x=72

13x+20=72

13x=72-20

13x=52

x=52÷13

x=4

How old is Martha?

x+5

4+5=9 years old