Используем распределительное свойство умножения: a ⋅ (b + c) = a ⋅ b + a ⋅ c
5 ⋅ (8 + 4t) = 5 ⋅ 8 + 5 ⋅ 4t = 40 + 20t
Ответ: 40 + 20t