x-(40%x+5)-[(40%x+5)×80%]=12
x-(0.4x+5)-(0.4x+5)×0.8=12
x-0.4x-5-(0.32x+4)=12
0.6x-5-0.32x-4=12
0.28x-9=12
0.28x=21
x=21/0.28
x=75
x一(4o%x十5)一[(40%x十5)x80%]=12的方程算式怎么解
x-(40%x+5)-[(40%x+5)×80%]=12
x-(0.4x+5)-(0.4x+5)×0.8=12
x-0.4x-5-(0.32x+4)=12
0.6x-5-0.32x-4=12
0.28x-9=12
0.28x=21
x=21/0.28
x=75