8x-4x=0.64
4x=0.64
x=0.64÷4
x=0.16
0.2x-x=416
-0.8x=416
x=416÷(-0.8)
x=-520
7x+2.5x=3.8
9.5x=3.8
x=3.8÷9.5
x=0.4
(3.8-2)x=14.4
1.8x=14.4
x=14.4÷1.8
x=8
希望对您有所帮助