Subject: Elimination/Substitution

Name: Jennifer
Who is asking: Teacher
Level: Secondary

Question:
Could I get an answer to this one:

2x+5y=36
3x+2y=32

I have to use the Elimination method, as I already know how to do Substitution. How do I begin and show my work? I'm attempting to eliminate the values for y.

Hi Jennifer,

To eliminate y you need to write two equations that are equivalent to the two that you have, but with the coefficient of y in the two equations the same. That way, if you subtract the two equations, the terms involving y will drop out. For the equations that you have the easiest way to do this is to multiply the first equation by 2 and the second by 5 to get

2(2x+5y) = 2(36)
5(3x+2y) = 5(32)

or

  4x+10y =   72
15x+10y = 160

Subtracting the first equation from the second leaves

11x = 88 so x = 8.

Now substitute x = 8 into either of the two equations that you started with to get the value of y.

Cheers,
Penny Math Central

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