1) 780:(x-24)+25=90
780:(x-24)=90-25=65
x-24=780:65
x-24=12
x=24+12=36
x=36
2) 31-y:350*8=200
31-y:350=200:8
31-y:350=25
y:350=31-25=6
y=350*6
y=2100
3)11x+9:4-26=45
11x+9:4=71
11x+9=71*4=284
11x=284-9=275
x=275/11
x=25
4) (3y+4+3y+y):37=52-50
(7y+4) :37=2
7y+4=37*2
7y+4=74
7y=70
y=10