The equation x + px + q = 0, where p and q are constants, has roots

The equation x² + px + q = 0, where p and q are constants, has roots −1 and 4.

a) Find the values of p and q.

b)
Using these values of p and q, find the value
of r, where r is a constant, and the equation
x² + px + q + r = 0 has equal roots.