If $h ( x ) = \frac { 4 } { 5 } x ^ { 3 } - 2 x + 5$, use sigma notation to write Riemann sums to approximate $A(h, 10 ≤ x ≤ 15)$ with $10, 20,$ and $100$ left endpoint rectangles of equal width. Then, use your calculator to find these approximations. What happens as the number of rectangles increases?