Q: Lizzie has half as many crayons as Bobbie. Bobbie has three times as many crayons as Billie. If Billie has 18 crayons, how many crayons does Lizzie have?
A: Bobbie has 18 * 3 = 54 crayons. Lizzie has 54 / 2 = 27 crayons. The answer is 27.

Q: Andy is checking to see if all the cars in the parking lot paid for their parking. 75% of the cars have valid tickets, and 1/5th that number have permanent parking passes. If there are 300 cars in the parking lot, how many people tried to park in the lot without paying?
A: First find how many cars have valid tickets: 75% * 300 cars = 225 cars. Then find the percentage of cars with parking passes: 75% / 5 = 15%. Then multiply that number by the total number of cars to find the number with parking passes: 15% * 300 cars = 45 cars. Then subtract all the cars with valid forms of parking to find the number parked illegally: 300 cars - 225 cars - 45 cars = 30 cars. The answer is 30.

Q: Dorothy is 15 years old and wants to go to a museum with her family. Her family consists of her, her younger brother, her parents, and her grandfather. The regular ticket cost is $10. People 18 years old or younger have a discount of 30%. How much money will Dorothy have after this trip, when she currently has $70?
A:
The discount per one ticket is 10 * 30 / 100 = $3. So Dorothy's and her brother's tickets are cheaper by 2 * 3 = $6. Her family consists of 5 people, so the ticket cost stands at 5 * 10 = $50. Including the discount will lower the price to 50 - 6 = $44 in total. Dorothy will be left with 70 - 44 = $26. The answer is 26.