800:2:2-a=148
400:2-a=148
200-a=148
a=200-148
a=52
600:a=6:3
600:a=2
a=600:2
a=300
a-400:(20:10)=357
a-400:2=357
a-200=357
a=357+200
a=557
a+700-700:7=777
a+700-100=777
a+700=777+100
a+700=877
a=877-700
a=177
3×300:3-a=235
900:3-a=235
300-a=235
a=300-235
a=65
0×600:3+a=600
0:3+a=600
0+a=600
a=600-0
a=600
a+500:(500:10:10)=500
a+500:(50:10)=500
a+500:5=500
a+100=500
a=500-100
a=400
60×10:3-a=53
600:3-a=53
200-a=53
a=200-53
a=147
