Question

what is the solution to this system of linear equations?
y=-9x+20
y=6x-25

Answer 1

6x-25=20-9x
15x=45
x=3
put this value in any equation
y=6*3-25=-7

Answer 2

We know that y should equal both right hand sides, so equate them:
\[ -9x+20=6x-25 \\
45=15x \\
x=3 \]
Now we can get y by inserting x into one of the original equations:
\[ y=6x-25=3*6-25=18-25=-7 \]