What's y=−3x−7 y=x+9 graphed?

Question

How do the equations look like when graphed and what does x and y equal?

Answer 1

These are 2 intersecting straight lines and the intersection is the solution of the simultaneous set.

 

The easiest way to solve this is to set the 2 expressions for y = to each other:

3x - 7 = x + 9

2x = 16

x = 8

y = 17