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Posted by **im stuck on this one!!** on Tuesday, January 18, 2011 at 10:55pm.

m+2n=1 5m+3n=-23

please step by step so that i could understand

- algebra 1 -
**MathMate**, Tuesday, January 18, 2011 at 11:19pmSubstitution means we express one variable in terms of another, and substitute this expression into the second equation.

m+2n=1 ...(1)

5m+3n=-23 ...(2)

From (1), we have

m+2n=1

subtract 2n from each side to get

m+2n-2n=1-2n

m=1-2n ...(1a)

Substitute m from (1a) into (2) to get:

5m+3n=-23

5(1-2n)+3n=-23

5-10n+3n =-23

-7n = -23 -5

-7n = -28

n=(-28)/(-7)=4 ...(2a)

Substitute n from (2a) into (1a)

m=1-2n

=1-2*4

=-7

So m=-7, n=4

Last step!!

Substitute the values of m and n into equations (1) and (2) to verify that the solutions are correct:

m+2n=1 ...(1)

-7+2*4=-7+8=1 OK

5m+3n=-23 ...(2)

5*(-7)+3*4

=-35+12

=-23 OK

- algebra 1 -
**im stuck on this one!!**, Tuesday, January 18, 2011 at 11:25pmTHANKS!!!!!!! great explaining!!!

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