7*х+21=100-16, х:121-1265=3647, 787*х=7286=20 259, 120+х*3=375, 24000:(х-12)=80, х:26+1654=2610

7x+21=100-16            
7x=84-21
7x=63
x=63:7
x=9
x:121-1265=3647
x:121=3647+1265
x:121=4912
x=4912*121
x=594 352
787x-7286=20 259
787x=20 259 + 7286
787x=27 545
x = 27 545 : 787
x = 35

120+x3=375
x3=375-120
x3=255
x=255:3
x=85
24000:(x-12)=80   
Х-12= 24000:80
Х-12=300
Х= 300+12
Х=312
x:26+1654=2610
x:26=2610-1654
x:26=956
x=956*26
x=24856