Q: Nicole collected 400 Pokemon cards. Cindy collected twice as many, and Rex collected half of Nicole and Cindy's combined total. If Rex divided his card equally among himself and his three younger siblings, how many cards does Rex have left?
A: Cindy has 400 x 2 = 800 cards. Nicole and Cindy have 400 + 800 = 1200 cards. Rex has 1200 / 2 = 600 cards. Rex is left with 600 / (3 + 1 = 4) = 150 cards. The answer is 150.

Q: Brian goes fishing twice as often as Chris, but catches 2/5 times fewer fish than Chris per trip. If Brian caught 400 fish every time he went fishing, how many fish did they catch altogether if Chris went fishing 10 times?
A: If Brian caught 400 fish in one trip, he caught 2 * 400 = 800 fish in two trips. Since Brian catches 2 / 5 times less fish than Chris per trip, Chris catches 2 / 5 * 400 = 160 more fish in one fishing trip. Chris's total number of fish in one trip is 400 + 160 = 560 fish. In 10 trips, Chris catches 560 * 10 = 5600 fish. If in his two trips Brian catches 800 fish, and he goes fishing twice as often as Chris, if Chris goes fishing 10 times, Brian will catch 800 * 10 = 8000 fish. The total number of fish they'll catch if Chris goes fishing ten times is 8000 + 5600 = 13600. The answer is 13600.

Q: Hally and her friends organized a high school reunion. To cover the cost of a late-night party that they planned for at the reunion, each attendee had to pay $100. After the party, Hally and her friends realized that the total expenses were $500 less than the total contributions. If there were 50 people at the party, how much money was used to pay for the party expenses?
A:
The total planned cost for the party was 100 * 50 = $5000. The total expenses for the party are 5000 - 500 = $4500. The answer is 4500.