Answer :
[tex]\frac{1}{2}(10p-7q)[/tex]
Evaluate the expression for p = 9 and q = 2:
[tex]\begin{gathered} \frac{1}{2}(10(9)-7(2)) \\ \frac{1}{2}(90-14) \\ \frac{1}{2}(76)=38 \\ \end{gathered}[/tex]