Question

Joan is 5 years older than ellen, and 3 years ago the sum of their ages was 17 years. in how many years will joan be 21 years old?

Answer 1

In 7 Years

Explanation:

Ellen's age = x

Joan's age = x + 5

3 Years ago

(x-3)+(x+5-3)=17

2x+5-6=17

2x=18

x=9

Hence Joan's age is 9+ 5 = 14

21 - 14 = 7

In 7 years Joan will be 21 years old

Answer 2

For this case, the first thing we must do is define variables.
We have then:
x: number of years of Joan y: number of years of ellen We now write the system of equations:

`y = x + 5 (x-3) + (y-3) = 17`
Solving the system we have:

`x = 9 y = 14`
So that Joan is 21 years old then:

`j + 9 = 21 j = 21 - 9 j = 12`
Answer:
joan will be 21 years old in 12 years