Answer:
n = pq + (x + 3) r
n = pq + rx + 3r {Get rid of the brackets}
n - pq - 3r = rx {Make the x lonely}
[tex] \frac{n - pq - 3r}{r} = \frac{rx}{r} [/tex]
{divide by the r that is multiplied by x to get rid of the r}
[tex] x = \frac{rn−pq−3r}{r} [/tex]