Solve using the multiplication principle first. Then use the elimination method: 7p+5q=2 8p-9q=17?

Multiply the first equation by 8 and the second equation by 7.
  8(7p + 5q) = 8(2)
  56p + 40q = 16
  7(8p - 9q) = 7(17)
  56p - 63q = 119
Subtract the result of the second multiplication from the results of the first.
  (56p + 40q) - (56p - 63q) = 16 - 119
  103q = -103    (notice that p is eliminated)
  q = -1
Substitute this result into the first equation.
  7p + 5(-1) = 2
  7p = 7
  p = 1
The solution is (p, q) = (1, -1).

-14x>-56