TMUA 2018 Paper 1 Question 12

A curve has equation $y=f(x)$, where $f(x)=x(x-p)(x-q)(r-x)$ with $0<p<q<r$. You are given that ${\int }_0^{r}f(x)dx=0$, ${\int }_0^{q}f(x)dx=-2$, and ${\int }_p^{r}f(x)dx=-3$. What is the total area enclosed by the curve and the $x$-axis for $0\le x\le r$?