We can model both situations with the equation of a straight line. Remember that such expression is:
[tex]y=mx+b[/tex]Where m is the slope, and b is the intercept with the x axis.
For this kind of situations, b would mean a fixed fee (equipment fee, in this case) and m would mean a variable fee (fee per hour of work)
In the context of the problem, that would mean that:
[tex]\begin{gathered} A=45t+275 \\ B=65t+175 \end{gathered}[/tex]Where t is the hours of work elapsed.
If we want to find out how much does each company charge for the 3 hours of
landscaping Gabriella needs, we'll just ned to replace t for 3
[tex]\begin{gathered} A=45(3)+275\text{ }\rightarrow\text{ }A=410 \\ B=65(3)+175\text{ }\rightarrow\text{ }B=370 \end{gathered}[/tex]So company B would be cheaper.