Are you sure you have enough math for this course? This is not going to be easy if linear equation are foreign to you.
A simple model of production might be to break revenue into two components, 1) profit and 2) cost to produce. Thus Revenue = Profit + Cost. This model, with a little algebra, is exatly what "someone said".
We are given Profit and Cost. Simply adding them is sufficient.
(0.6x - 14.5) + (0.8x + 14.5)
After that, it is an algebra problem.
Note: If you are focused on the concept of slope and intercept, and cannot see just the algebra, you will continue to struggle. You do NOT have to know the meaning of each little symbol before you write it. Sometimes, you can just let the notation be the notation and move on. Get good at manipulating the notation. You are very unlikely to do this if you are hung up on the specific meaning of every jot and tittle.