(y : 16) ⋅ 13 + 12 = 51
(y : 16) ⋅ 13 = 51 - 12
(y : 16) ⋅ 13 = 39
y : 16 = 39 : 13
y : 16 = 3
y = 3 ⋅ 16
y = 48
Ответ: 48