# SOLUTION: Soluve using the multiplication principle first. Then use the elimination method: 7p+5q=2 8p-9q=17 I know a common number needs to be found but how do I choose which one?

Algebra ->  Algebra  -> Equations -> SOLUTION: Soluve using the multiplication principle first. Then use the elimination method: 7p+5q=2 8p-9q=17 I know a common number needs to be found but how do I choose which one?       Log On

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 Click here to see ALL problems on Equations Question 373980: Soluve using the multiplication principle first. Then use the elimination method: 7p+5q=2 8p-9q=17 I know a common number needs to be found but how do I choose which one? Thanks!Answer by Alan3354(31518)   (Show Source): You can put this solution on YOUR website!7p+5q=2 8p-9q=17 --------- You can eliminate either p or q. In this case, it's 7 & 8 or 5 & 9. I'll do 5 & 9 7p+5q=2 --> 63p + 45q = 18 8p-9q=17--> 40p - 45q = 85 ----------- 63p + 45q = 18 40p - 45q = 85 -------------- Add 103p = 103 p = 1 ------ 7p+5q=2 7 + 5q = 2 5q = -5 q = -1