Answer to the solution

y=-5x+10
An solution is coordinate which line goes through for example if we use (0,0) or (2,0) if the coordinate are right that mean it is ture. (X,Y)
(0,0)
0=-5(0)+10
0=0+10
0=10
NOT SOLUTION

(2,0)
0=-5(2)+10
0=-10+10
0=0
SOLUTION

That mean that the line is goes through the solution (2,0). The line is ture.

This system is called substition