把以下方程的过程写出 90-（x-4)=42 3x0.7+x+3x=6.5 8x(x-0.1)=48 8x÷2=1 34x-5x+48=106 (x-3)+5x=27

90-（x-4)=42 90-x+4=4290+4-42=xx=523x0.7+x+3x=6.5 2.1+4x=6.54x=4.4x=4.4/4x=1.18x(x-0.1)=48 x-0.1=48/8x-0.1=6x=6.18x÷2=1 8x=1*28x=2x=2/8x=1/434x-5x+48=106 34x-5x=106-4839x=58x=58/39(x-3)+5x=27x-3+5x=2...