Question: After Betty gave Stuart 40% of her marble collection, the number of marbles in Stuart's collection increased to 80. If Betty had 60 marbles, how many marbles did Stuart have initially?
Answer with step-by-step thinking: If Betty had 60 marbles, she gave Stuart 40 / 100 * 60 = 24 marbles. Since the number of marbles in Stuart's collection increased to 80 after Betty gave him 24 marbles, the number of marbles he initially had is 80 - 24 = 56.
So the answer is 56.

Question: Pauly is making ice cubes. He needs 10 pounds of cubes. He knows that 2 ounces of water make 1 cube and each cube weighs 1/16th of a pound. It takes him 1 hour to make 10 cubes. Every hour his ice maker run costs $1.50. Every ounce of water costs $0.10. How much will it cost to make all the ice?
Answer with step-by-step thinking: He needs 160 ice cubes because 10 / (1 / 16) = 160. It will take him 16 hours because 160 / 10 = 16. His ice maker will cost $24 to run because 16 x 1.5 = 24. He will need 320 ounce of water because 160 x 2 = 320. This will cost him $32 because 320 x .1 = 32. It will cost in total $56 to make all the ice because 24 + 32 = 56.
So the answer is 56.

Question: Mark buys a loaf of bread for $4.20 and some cheese for $2.05. He gives the cashier $7.00. If the cashier only has 1 quarter and 1 dime in his till, plus a bunch of nickels, how many nickels does Mark get in his change?
Answer with step-by-step thinking:
First subtract the cost of Mark's groceries from the amount he gives the cashier to find how much he gets in change: $7.00 - $4.20 - $2.05 = $0.75. Then subtract the value of a quarter in cents (25) and the value of a dime in cents (10) from the change amount to find how much Mark gets paid in nickels: $0.75 - $0.25 - $0.10 = $0.40. Now divide the amount Mark gets in nickels by the value per nickel in cents (5) to find how many nickels Mark gets: $0.40 / $0.05 / nickel = 8 nickels.
So the answer is 8.