(3a-2b)/(a-b) а дальше также
5х+80=690
5х=690-80
5х=610
Х=610:5
Х=122
1)70:4=17.5
2)17.5*100=1750
3)1750-100=1650
1. (40*2)-3=80-3=77
2. (100:2)-31=50-31=19
3. (60:2)+45=30+45=75
4. (100:5)-12=20-12=8
5. (80:2)+51-38=40+51=91-38=53
6. (100:10)+43-38=10+43=53-38=15
7. (60:2)+50-40=30+50=80-40=40
8. (20*3)+(90-62)=60+28=88
9.(20*3)+(92-60)=60+32=92
10. (80:2)+32-56=40+32=72-56=16
11. 50*(80:40)=50*20=1000
12.30*(90:30)=30*20=6000
13. 90:(3*10)=90:30=3