SOLUTION: Solve the following 2 x 2 systems using substitutions 3x - y = 5 6x + 5y =-18

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Question 72319: Solve the following 2 x 2 systems using substitutions
3x - y = 5
6x + 5y =-18
Answer by elima(1433) About Me  (Show Source):
You can put this solution on YOUR website!
3x - y = 5
6x + 5y =-18
Take the first equation and change it around so we have;
-y = 5 - 3x
y = 3x - 5
Now plug that into the second equation for y;
6x + 5(3x - 5)= -18
6x + 15x - 25 = -18
21x = -18 +25
21x = 7
x = 7%2F21 = 1%2F3
Now plug that into the equation for x;
3({{1/3}}}) - y = 5
3%2F3 - y = 5
1 - y =5
-y = 5-1
-y = 4
y = -4
:)