SOLUTION: What is the elimination method for 3x-5y=30 and 5x+7y=4

Question 657727: What is the elimination method for 3x-5y=30 and 5x+7y=4
Answer by chriswen(106) (Show Source): You can put this solution on YOUR website!
Okay for elimination we need to eliminate something. I'll choose to eliminate x. I need both x's to be equal. So I'll multiply the first equation by 5 and the second equation by 3.
3x-5y=30 ... (i)
15x - 25y = 150 ... (iii)
5x + 7y = 4 ... (ii)
15x + 21y = 12 ... (iv)
Now eliminate. I will subtract equation 4 from equation 3.
15x - 25y = 150
-)15x+21y = 12
________________
0x -46y = 138
y = -138/46
y = 3
now I will sub y = 3 into equation 1.
3x - 5(3) = 30
3x - 15 = 30
3x = 45
x = 45/3
x = 15
Therefore, x = 15, y = 3. This was solved via elimination method.
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