Normally I wouldn't post the question straight out of the book, but today I am desperate because I just cannot get any bearing on this one.

Triangular numbers of objects can be arranged to form triangles. The first four triangle numbers are: 1, 3, 6, 10.

a)an expression to find the nth triangular number can be written in the form n(n+p)/q where p and q represent whole numbers. Complete the expression by determining the numbers represented by p and q.