Sally is four years older than John. John is nine years older than Karen. If the sum of their ages is 85, how old are they?

Answer 1

k = Karen's age

k + 9 = John's age

(k + 9) + 4 = Sally's age = k + 13

k + (k + 9) + (k + 13) = 85

3k + 22 = 85

3k = 63

k = 21 (Karen is 21)

k + 9 = 21 + 9 = 30 (John is 30)

k + 13 = 21 + 13 = 34 (Sally is 34)

Note that 21+30+34=85

Answer 2

Symbolizing the ages, let S = Sally’s age, J = John’s age, K = Karen’s age. Then

S = J + 4. J = K + 9. K = K

Solve for J: 3J = 85+9-4 = 90. So, J = 30, S = 34, and. K = 21