<span>3t+7t+18=108
</span>10t = 108 - 18
10t = 90
t = 90 : 10
t = 9
а-б=3/5
а=4б
4б-б=3/5
3б=3/5
б=(3/5)/3=3/15 сократи дробь=1/5
тогда а=4*(1/5)=4/5
2/3 = 2х20/3х20 = 40/60
1/2 = 1х30/2х30 = 30/60
3/4 = 3х15/4х15 = 45/60
1/6 = 1х10/6х10 = 10/60
4/15 = 4х4/15х4 = 16/60
7/20 = 7х3/20х3 = 21/60
11/30 = 11х2/30х2 = 22/60
Вроде так