$($d$)$ The sum ${\displaystyle \underset{k=1}{\overset{n}{}}}{h}^{\text{'}}(\frac{15}{n}(k-1))\frac{15}{n}$ is a left Riemann sum with $n$ subintervals of equal length. The limit of this sum as $n$ goes to infinity can be interpreted as a definite integral. Express the limit as a definite integral. $($Show all your work please$)$