Let A represent the amount Ann contributed, Z represent Zoe's contribution, and J represent Jim's contribution toward the present.
Ann (A): A
Zoe (Z): A = Z - 12 → Z = 12 + A
Jim (J): A = J - 16 → J = 16 + A
A + Z + J = 154
(A) + (12 + A) + (16 + A) = 154
3A + 28 = 154
3A = 126
A = 42
Ann (A): A = 42
Zoe (Z): Z = 12 + A = 12 + 42 = 54
Jim (J): J = 16 + A = 16 + 42 = 58
Answer: Ann=42, Zoe=54, Jim=58
