Rita is 12 years old and her father is 39 years old. In how many years will Rita be twice as young as her father?

## Rita is 12 years old and her father is 39 years old. In how many years will Rita be twice as young as her father?

Tutors, please sign in to answer this question.

# 3 Answers

2(12 + n )= (39 + n) (1)

24 + 2n = 39 +n

n = 39 -24 = 15

After 15 years Rita 's age = 12 + 15 = 27, father age = 39 +15 = 54

54 = 2 ( 27).

Notice that whole word problem was put into one algebraic statement of equation (1).

Moshe,

Another less intuitive way to do this problem….

Let A

_{f}=t+39, the fathers age, t is time in years (t=0 now)and A_{d}=t+12, the daughters age then we want to calculate at what time will A_{d}=A_{f}/2 so we must have t+12=(t+39)/2, solving this equation for t gives t=15 years. In 15 years Rita will be 15+12 or 27 years old and her father will be (15+39)/2 =54 years old.Jim

Subtract the two ages:

39 - 12 = 27

Rita will be half as old (twice as young) as her father when she is 27 - or in 15 years.