Sam borrows money from his brother to buy a new video game. He agrees to pay his brother back the full amount of the loan, plus an additional $4.50, which is 9% interest. How much did Sam borrow originally?
Sam borrowed 50 dollars. Since 4.50 is 9% and 9% is so close to 10% I rounded up to 5 is 10% as a guess. Doing this, I multiplied both by ten to get 50=100%. To check, I multiplied 50 by .09 (9%) and got 4.5
