а) 3(5/8) + 1(2/3) = 15/8 + 2/3 = 61/24
б)4(4/9)-2(5/6)=16/9 - 5/3 = 1/9
в)6*(7/12)+(5*(3/40)-4/(8/15)=7/2 - 57/8 = -29/8 = -3(5/8)
