57.6/18＝3.2
75*16=16X+80
91+4X=127
3x-0.9=2.4
2X-2=4
x2－4=0
x2－7=0
x2-9=0
4y2=9
16x2－49=0
2x2－32=0
t2－45=0
(6x－...