A + B + C = 82 (1) A + B = C + 86 (2) C = A - 61 (3) I chose to substitute "C+86" from (2) as "A+B" in (1): (C + 86) + C = 82 ==> 2C = -4 ==> C = -2 Plugging this result into (3) gives A = 59 Plugging the newly found A & C values into (1) or (2) gives B = 25 — Check: A + B + C = 59 + 25 - 2 = 82 (ok) A + B = 59 + 25 = 84 and C + 86 = -2 + 86 = 84 (ok) C = -2 and A-61 = 59-61 = -2 (ok)