(x+2.5)*3=503x=50-7.5=42.5x=85/6
X+2.5x3=50 X+7.5=50 X=50-7.5 X=42.5
x+2.5*3=50，即x=50-2.5*3，x=42.5
x＝50÷2.5×3
