If the coefficients of x and x^2 in the expansion of (1+x)^p (1-x)^q, p, q ≤ 15, are -3 and -5 respectively, then the coefficient of x^3 is equal to…

If the coefficients of $\displaystyle x$ and $\displaystyle x^2$ in the expansion of $\displaystyle (1+x)^{\mathrm{p}}(1-x)^{\mathrm{q}}, \mathrm{p}, \mathrm{q} \leq 15$, are -$\displaystyle 3$ and -$\displaystyle 5$ respectively, then the coefficient of $\displaystyle x^3$ is equal to \_\_\_\_.