a))
= 1/2 -2/3 X 3/5 +9/4
= 1/2- 2 x 1/5 + 9/4
= 1/2-2/5 + 9/4
= 10/20 - 8/20 + 45/20
= 47/20
B))
(3/5-2/7x7/20):(1/2-2/5)+1/8
= (3/5-1/10):(5/10-4/10)+1/8
= (6/10-1/10):1/10 +1/8
= 5/10 x 10 + 1/8
= 50/10 + 1/8
= 5 + 1/8
= 40/8 + 1/8
= 41/8
Sper ca te-am ajutat !