Question: Carolyn buys a silverware set with 6 knives, 12 forks, and three times as many spoons as knives. Then her friend trades her 10 knives for 6 spoons. What percentage of Carolyn's silverware is knives?
Answer with step-by-step thinking: First find the final number of knives Carolyn has: 10 knives + 6 knives = 16 knives. Then find the initial number of spoons Carolyn has: 6 knives * 3 spoons / knife = 18 spoons. Then find the final number of spoons Carolyn has: 18 spoons - 6 spoons = 12 spoons. Then find the total final amount of silverware Carolyn has: 12 spoons + 16 knives + 12 forks = 40 pieces. Then divide the number of knives by the total number of pieces and multiply by 100% to express the answer as a percentage: 16 knives / 40 pieces * 100% = 40%.
So the answer is 40.


Question: Tom finds 10 quarters, 3 dimes, and 4 nickels and 200 pennies. In dollars, how much money did he find?
Answer with step-by-step thinking: He found 10 * .25 = $2.5 in quarters. He found 3 * .1 = $.3 in dimes. He found 4 * .05 = $.2 in nickels. He found 200 * .01 = $2 in pennies. So in total, he found $2.5 + $0.3 + $0.2 + $2 = $5.
So the answer is 5.


Question: Billy and Margaret are competing with each other to see who can swim 10 laps the fastest. Billy swims his first 5 laps in 2 minutes, swims the next 3 laps in 4 minutes, swims the next lap in 1 minute, then swims his final lap. Margaret finishes swimming all of her laps in 10 minutes. Billy wins the competition by finishing his laps 30 seconds before Margaret does. In seconds, how long did it take Billy to swim his final lap?
Answer with step-by-step thinking:
Margaret finished all of her laps in 10 minutes * 60 seconds = 600 seconds. Billy’s first 5 laps took 2 minutes * 60 seconds = 120 seconds. His next 3 laps took 4 minutes * 60 seconds = 240 seconds. His ninth lap took 1 minute * 60 seconds = 60 seconds. So his first 9 laps took 120 + 240 + 60 = 420 seconds. Billy finished swimming his laps before Margaret so all of his laps took a total of 600 – 30 = 570 seconds. This means that it took 570 seconds in total swimming time – 420 seconds in time spent swimming the first 9 laps = 150 seconds for Billy to swim his final lap.
So the answer is 150.