7 × (3 + k) = 33 + 5k
21 + 7k = 33 + 5k
7k – 5k = 33 – 21
2k = 12
k = 12 ÷ 2
k = 6
Проверка:
7 × (3 + 5) = 33 + 5 × 6
7 × 8 = 30 + 33
63 = 63
3b – 2 + 6b – 8b = 10
b – 2 = 10
b = 10 + 2
b = 12
Проверка:
3 × 12 – 2 + 6 × 12 – 8 × 12 = 10
34 + 72 – 96 = 106 – 96 = 10
10 = 10