Question: James bought a gallon of milk for $3, a bunch of bananas for $2, and paid 20% sales tax. How much money did James spend?
Answer: First add up James' purchases that is $3 + $2 = $5. So, the amount of sales tax is $5 * .2 = $1. Hence, James spent a total of $5 + $1 = $6. The answer is 6.

Question: Anna can read 1 page in 1 minute. Carole can read as fast as Anna but at half the speed of Brianna. How long does it take Brianna to read a 100-page book?
Answer: If Anna can read 1 page in 1 minute, then her speed is 1 / 1 = 1 page per min. If Carole can read at Anna's same speed then her speed is also 1 page per min. If Carole is only half the speed of Brianna, then that means Brianna is twice as fast as Carole, so 2 * 1 page per min = 2 pages per min. If a book is 100 pages long and Brianna can read 2 pages per minute, then it will take her 100 / 2 = 50 minutes to read the book. The answer is 50.

Question: Mara has 40 crayons and 10 percent of her crayons are pink. Luna has 50 crayons and 20 percent of them are pink. In total how many pink crayons do Mara and Luna have?
Answer: Mara has 40 x (10 / 100) = 4 pink crayons. Luna has 50 x (20 / 100) = 10 pink crayons. Together they have 4 + 10 = 14 pink crayons. The answer is 14.

Question: Class A is twice as big as Class B. Class A is also a third the size of Class C. If Class B has 20 people in it, how many people are in Class C?
Answer:
Class A is twice the size of Class B, so Class A = 2 * size of Class B. If Class B has 20 people Class A has 20 * 2 = 40 people. Since Class A is also 1 / 3 the size of Class C then Class A = 1 / 3 * Class C. This means 40 = 1 / 3 * Class C. Thus the size of Class C is 3 * 40 = 120 people. The answer is 120.