Question

In 5 years, Dad will be three times as old as his daughter Jill will be then. If the sum of their present ages is 50, how old are they now?

If x + 5 is Jill's age five years from now, which of the following equations could be used to solve the problem?

3x + 5 = 55 - x
3x + 15 = 55 - x
3x + 15 = 45 - x

Answer 1

let D = dad's age now.
let J = jill's age now.
D+5 = dad's age 5 years from now.
J+5 = jill's age 5 years from now.
problem states that the sum of their ages now is 50, so
D+J=50
problem states that in 5 years dad will be 3 times as old as jill will be then, so
(D+5) = 3 * (J+5)
to solve this problem, we remove one of the unknowns by expressing it in terms of the other unknown in one of the equations.
i took D+J=50 because it was simpler. i could have used the other equation as well. either way it will work.
if D+J=50, then D=(50-J)
taking that relationship and substituting for D in the other equation, it becomes
50 - J + 5 = 3 * (J + 5)
this becomes
50 - J + 5 = (3 * J) + (3 * 5)

Answer 2

DId that help?

Answer 3

yes it did thank you