25%x=75%
x=75%÷25%
x=3
50%x-25%x=25
25%x=25
x=25÷25%
x=100
x+31%=39.3
x=39.3-31%
x=39.3-0.31
x=38.99
x-18%=65.6
x=65.6+18%
x=65.6+0.18
x=65.78
20x-30=150
20x=150+30
20x=180
x=98x=42=48应该是8x+42=48吧？8x=48-428x=6x=3/4x=0.75