Answer:
A = (2/7 + 4) × 3/7
= (4 + 2/7) × 3/7
= (28/7 + 2/7) × 3/7
= (30/7) × 3/7
= (90/49)
B = -1/5 × 3/2 + 6/4
= -3/10 + 6/4
= -3/10 + 15/10
= (12/10)
= (6/5)
C = (3/7 + 1) × (3/7 - 1)
= (10/7) × (-4/7)
= (-40/49)
D = 9/7 - (3/7 × 2/5) + 1
= 9/7 - 6/35 + 1
= 45/35 - 6/35 + 35/35
= (45 - 6 + 35)/35
= (74/35)
Explanation: