1. Rieman sum

find the midpoint Riemann sum approximation of $\int_{1}^{5} f(x)dx$ by dividing into two equal subintervals using the given values of x and f(x)

x | f(x)
1 15
2 10
3 9
4 6
5 5

the two intervals should be 1 to 3 and 3 to 5.

I am getting anything but 14