Great! So let’s solve for Joe’s Plumbing charges first. To find his price for 3 hours, solve J(3)=45(3)=$135.
Now let’s find Mark’s Plumbing charges. To find his price for 3 hours, plug 3 into M(t)=40t+25. So, M(3)=40(3)+25=$145.
Therefore, Joe’s Plumbing is cheaper than Matt’s plumbing by 10 dollars for a 3 hour job.