Expert: Richard J. Raridon - 9/28/2004

Question
I need your help, hopefeully you'll know these problems cause I've been having problems with these certain ones for a while now and i could really use some help. Here are the problems.

1. 2x+y=18
  2x-y=22

2. 12a-5b=18
  15a-5b=30

This one you gotta solve by the substituion or the addition and subtraction method.

3. 2m=n-3
  3m=2n-9

Answer
1. Just add the equations together and you have 4x=40, so
x = 10 and y = -2
2. Subtract the 2nd eq. from the 1st to get -3a = -12, so
a = 4 and b = 6
3. multiply the 1st eq. by 2 to get 4m = 2n-6.
subtract the 2nd eq. to get m = 3 and therefore n = 9