Help me on how to solve these finanical math questions!?

Question

Im trying to get a hold of a book for this class so I can learn on my own, but I want to know how to solve these questions. Can someone please help me!!!?? Our professor gave us these 3 basic formulas, but i am still a little lost.
C+Pr=P, MA= Pr/P, MU=Pr/C

1. The markup on an item is twice it's margin. The profit is $50. Find the margin on this item.

2. The markup on an item is twice it's margin. The profit is $800. Find the markup on this item.

Answer 1

Become a small businessman and you'll learn fast enough.

1. margin= profit/price
markup = 2 profit/price (from problem)
markup = profit/cost
But cost=price-profit
Then markup= profit/(price-profit)= 2 profit/price
Since we know profit is 50,
50/[price-50] = 100/price, price = 100
margin=1/2
2. The same set-up as above applies, except that the profit is $ 800. So the price is $1600, cost is $ 800.
markup = 800/1600 = 1/2