Câu trả lời:

a>31,5 – x = (18,6 – 12,3) : 3

31,5 - x = 2,1

x = 31,5 - 2,1

x = 29,4

b>4.(-5/6)-x=7/12+-1/3

-10/3-x=1/4

x=-10/3-1/4

x=-43/12

c>1/2-1/2x=2/3

1/2x=1/2-2/3

1/2x=-1/6

x=-1/6:1/2

x=-1/3