23/24-1/8=(23-1*3)/24=20/24=5/6
7 4/5*(-2/14)=-(39*2)/5*14=-39/35
5/6*(-39/35)=-39/42=-13/14 это ответ
10у + 14у - 4 = 20у + 15 + 3у
10у + 14у - 20у - 3у = 15 + 4
у = 19
y-2/8 = 3y-4/3 | :24
24(y-2)/8 = 24(3y-4)/3
3(y-2) = 8(3y-4)
3y-6 = 24y-32
26 = 21y
y=26/21