SOLUTION: Solve the system using the substitution method. Show work X-4y=-65, y=-3x

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Question 1093432: Solve the system using the substitution method. Show work
X-4y=-65, y=-3x
Answer by ikleyn(52781) About Me  (Show Source):
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Because in the second equation the unknown "y" is just expressed via "x".


So, all you need to do is to replace "y" in the first equation by (-3x).

Then you get the single equation for one unknown y:

x - 4*(-3x) = -65,

x + 12x = - 65  ====>  13x = -65  ====>  x = -65%2F13 = -5.


Last step is to find y.  For it, substitute x= -5 into your second original equation to get y = -3*(-5) = 15.


Answer.  x = -5,  y = 15.