Isabella wishes to buy gasoline and have her car washed. She finds that if she buys 9 gallons of gasoline at $1.50 per gallon, the car wash costs $1, but if she buys 10 gallons of gasoline, the car wash is free. For Isabella, the marginal cost of the tenth gallon of gasoline is

Which of the following is a thrift institution?

i. a credit union ii. the Fed iii. a savings bank A) i only B) ii only C) iii only D) Both i and iii E) i, ii, and iii

If the quantity of donuts supplied is represented by the supply equation QS = -15 + 5P, then to solve for the price of donuts, the equation would be rewritten as

A) P = 5QS + 75. B) P = 15 - 0.5QS. C) P = QS - 7.5. D) P = 0.2QS + 3.