First, find the width of the rectangles
7-3 = 4
We ware using 4 rectangles
4/4 =1
delta x = 1
We are using the right side
So the values are at 4,5,6,7
The function evaluated at the right hand side times the width of the rectangle summed for the 4 rectangles
The summation is f(4) *1 + f(5) *1 + f(6) *1 + f(7) *1
4/(11(4)) *1 + 4/(11(5)) *1 + 4/(11(6)) *1 + 4/(11 (7)) *1
4/44 + 4/55 + 4/66 +4/77
29/105