I need help with a problem . Our instructor wants us to solve this problem using goal seek on excel. I have watched his videos over and over and yet I am still stumped. I am confused on how to enter in the right formulas. Here is the problem:

Tom Johnson Manufacturing intends to increase capacity through the addition of new equipment.Two vendors have presented proposals. The fixed cost for proposal A is $50,000, and for proposal B, $70,000. The variable cost for A is $12, and for B, $10. The revenue generated by each unit is $20.

1. A) Set up the given problem on MS Excel. Solve it using "Goal Seek" (3pts)
2. B) What is the BEP in units and in dollars for proposal A and B? (3pts)

Again, I'd like to figure the answer out on my own. I am just stuck on how to put in the formulas. Thank you!

Ashley