Answer:
a x (b + c) or a x (b - c)
4 × (11 + 10)
or
4 × (22 - 1)
Explanation:
20 + 64 = 84
84 ÷ 4 = 21
21 - 10 = 11
22 - 1 = 21
3.3m questions
4.2m answers