Đáp án:
a) ( 3/8 + -1/4 + 5/12 ) : 7/8 b) -5/7 × 2/11 + -5/7 × 9/11 + 1 và 5/7
= (9/24 + -6/24 + 10/24) × 8/7 = -5/7 × (2/11 + 9/11) + 12/7
= (3/24 + 10/24 ) × 8/7 = -5/7 × 1 + 12/7
= 13/24 × 8/7 = -5/7 + 12/7
= 13/21 = 7/7 = 1
c) 6/7 + 5/8 : 5 và 3/16 × (-2)²
= 6/7 + 5/8 : 83/16 × 4
= 6/7 + 5/8 × 16/83 × 4
= 6/7 + 10/83 × 4
= 6/7 + 40/83
= 498/581 + 280/581
= 778/581