1/5*(1+x)+1/3*(3x +1)=1
1/5 · (1 + х) + 1/3 · (3х + 1) = 1 3(1 + х) + 5(3х + 1) = 15 3 + 3х + 15х + 5 = 15 18х = 7 х = 7/18