(x+10):37=20
x+10=20*37
x+10=740
x=740-10
x=730
900:(x+5)=100
x+5=900:100
x+5=9
x=9-5
x=4
(a-20)*80=240
a-20=240:80
a-20=3
a=3+20
a=23
600:(a+20)=15
a+20=600:15
a+20=40
a=40-20
a=20
1250-5*x=225
5*x=1250-225
5*x=1025
x=1025:5
x=205
1250-x:5=1220
x:5=1250-1220
x:5=30
x=30*5
x=150
4800:(y-50)=6
y-50=4800:6
y-50=800
y=800+50
y=850
732+12*x=780
12*x=780-732
12*x=48
x=48:12
x=4