Bài 1:
a) 4/7 + 5/9 = 36/63 + 35/63 = 71/63
b) 19/4 - 7/3 = 57/12 - 28/12 = 29/12
d) 5/12 : 5/6 + 7/6 = 1/2 + 7/6 = 6/12 + 14/12 = 5/3
Bài 2:
a - 5/2 = 1/3
a = 1/3 + 5/2
a = 2/6 + 15/6 = 17/6
a x 3/7 = 1/5 x 6
a x 3/7 = 6/5
a = 6/5 : 3/7
a = 6/5 x 7/3 = 14/5
a : 1/5 = 3/8 : 7/6
a : 1/5 = 3/8 x 6/7
a : 1/5 = 9/28
a = 9/28 x 1/5 = 9/140