Answer:
7
Step-by-step explanation:
If J is Joan's current age and E is Ellen's current age, then:
J = E + 5
(J - 3) + (E - 3) = 17
Solve the first equation for E:
E = J - 5
Substitute into the second:
(J - 3) + (J - 5 - 3) = 17
J - 3 + J - 8 = 17
2J - 11 = 17
2J = 28
J = 14
Joan is 14, so in 7 years, she will be 21.
