1)x=1200
x/20+40=x/12
x/20+40-x/12=0
12x/240-20x/240+40=0
-8x/240+40=0
-8x=-40×240
x=-40/-8×240
x=5×240
x=1200
2)x=40
1200/20+x=1200/12
60+x=100
x=100-60
x=40