c) Tính: 28 × (10 – 1) =
c) Tính: 28 × (10 – 1) =
(100 – 1) × 36 =
28 × (7 – 2) = 28 × 7 – 28 × 2
= 196 – 56
= 140(14 – 7) × 6 = 14 × 6 – 7 × 6
= 84 – 42
= 42