Please help

What is 17 3/4 minus 8 7/12

First I'd note that

$\dfrac 3 4 = \dfrac 9 {12} > \dfrac 7{12}$ 

so

$17 \dfrac 3 4 - 8\dfrac 7{12} = (17-8) + \left(\dfrac 3 4 - \dfrac 7{12}\right)= \\ \\ 9 + \left(\dfrac 9{12}-\dfrac 7{12}\right) = 9+\dfrac 2{12} = 9\dfrac 1 6$