3X-3×3= 18
3X-9= 18
3X= 18+9
3X=27
x = 27 \3
X=9
2, X÷2= two thirds.
X÷2×2= two thirds× 2
X= four thirds
X= one and a third
3、 12(X+3.7)= 144
12X+ 12×3.7 = 144
12X+44.4= 144
12X= 144-44.4
12X=99.6
X=99.6÷ 12
X=8.3
4、5X-3× 1 1=42
5X-33=42
5X=42+33
5X=75
X= 15