Let s represent the number of sofas and e represent the amount earned.
We have been given that Mr. Gilmore sells furniture. He earned $210 for selling 3 sofas. Mr. Gilmore earned $570 for selling 11 sofas. We are asked to write the equation for given scenario.
We have two points on a line that are (3,210) and (11,570).
Let us find slope of line passing through these points.
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]
[tex]m=\frac{570-210}{11-3}[/tex]
[tex]m=\frac{360}{8}[/tex]
[tex]m=45[/tex]
Now we will use point-slope form of equation.
[tex]y-y_1=m(x-x_1)[/tex], where
m = Slope,
[tex](x_1,y_1)[/tex] = Any point on line.
[tex]y-210=45(x-3)[/tex]
[tex]y-210=45x-135[/tex]
[tex]y-210+210=45x-135+210[/tex]
[tex]y=45x+75[/tex]
Since amount earned is e and number of sofas is s, so our equation would be [tex]e=45s+75[/tex].
Therefore, our required equation would be [tex]e=45s+75[/tex].