Вычислите: (3/4-5/12)*8+1/18; б) 1/3*(3/5*5/7)+1/3*(5/9*9/7); в) 7/12*6/17+1/8: 17/6;

А) (3/4-5/12)*8+1/18 = 2 целых 13/18
    1) 3/4 - 5/12 = 1/3
    2) 1/3*8= 8/3
    3) 8/3+1/18= 49/18 = 2 целых 13/18
б) 1/3*(3/5*5/7)+1/3*(5/9*9/7)= 8/21
    1)3/5*5/7= 3/7
    2)5/9*9/7=5/7
    3)1/3*3/7=1/7
    4)1/3*5/7=5/21
    5)1/7+5/21=8/21
в) 7/12*6/17+1/8:17/6 = 1/4
    1)7/12*6/17 = 7/34
    2)1/8:17/6 = 3/68
    3)7/34+3/68=1/4