SOLUTION: Please solve by the elimination method. 5r-6s = 21 6r+5s = 74. What is the solution of the system? Type an ordered pair. Thank you.

Algebra ->  Expressions-with-variables -> SOLUTION: Please solve by the elimination method. 5r-6s = 21 6r+5s = 74. What is the solution of the system? Type an ordered pair. Thank you.      Log On


   

Question 198885: Please solve by the elimination method.
5r-6s = 21
6r+5s = 74.
What is the solution of the system? Type an ordered pair.
Thank you.
Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
Please solve by the elimination method.

system%285r-6s+=+21%2C+6r%2B5s+=+74%29

Eliminate s by multiplying the top equation by 5 and
the bottom equation through by 6

system%285%285r-6s%29+=+5%2821%29%2C+6%286r%2B5s%29+=+6%2874%29%29

system%2825r-30s+=+105%2C+36r%2B30s+=+444%29

Now add corresponding terms:

61r%2B0s=549

61r=549

r=549%2F61

r=9

Now switch over to substitution to find s

5r-6s+=+21

5%289%29-6s=21

45-6s=21

-6s=21-45

-6s=-24

s=%28-24%29%2F%28-6%29

s=4

So (r,s)=(9,4)

Edwin