In order to find the result we just have to replace x by the number into the parenthesis:
[tex]\begin{gathered} f(x)=x^2+7 \\ f(3)=3^2+7 \\ f(3)=9+7=16 \\ \\ h(x)=\frac{12}{x} \\ h(-2)=\frac{12}{-2}=-6 \\ \\ j(x)=2x+9 \\ j(7)=2\cdot7+9 \\ j(7)=14+9=23 \end{gathered}[/tex]