22.5-(3.2x-2.4x)÷3.2=10
22.5-0.8x÷3.2=10
22.5-
x=101 4
22.5-
x-10+1 4
x=10-10+1 4
x1 4
x=12.51 4
x×4=12.5×41 4
x=50
答:所填的数应该是50.