find the midpoint Riemann sum approximation of $\displaystyle \int_{1}^{5} f(x)dx$ 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 answer is 14 according to the answer key.

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

I am getting anything but 14