We have a question: It costs $.10 to print one page. Jenny wants to print 7 copies of her 25-page essay. She also wants to buy 7 pens that each cost $1.50. If she pays the store with 2 twenty dollar bills, how much money should she get in change?
And an answer: 12
So how you got the answer?
Jenny needs to print 7 * 25 = 175 pages. This will cost 175 * $.10 = $17.5. The pens will cost 7 * $1.50 = $10.50. In total, she will spend $17.5 + $10.5 = $28. Since she pays with 2 twenty dollar bills she pays with 2 * 20 = 40 dollars. Thus, she will get $40 - $28 = $12 in change.

We have a question: Lavinia's daughter is 10 years younger than Katie's daughter. Lavinia's son is 2 times the age of Katie's daughter. If Katie's daughter is 12 years old, how many years older is Lavinia's son than Lavinia's daughter?
And an answer: 22
So how you got the answer?
Lavinia's daughter is 12 - 10 = 2 years old. Lavinia's son is 12 * 2 = 24 years old. Lavinia's son is 24 - 2 = 22 years older than Lavinia's daughter.

We have a question: Gina had $400. She gave 1/4 of her money to her mom, used 1/8 of her money to buy clothes, gave 1/5 of her money to a charity, and kept the remaining money. How much did Gina keep?
And an answer: 170
So how you got the answer?
Gina's mom received 1 / 4 x $400 = $100. She used 1 / 8 x $400 = $50 to buy clothes. She gave 1 / 5 x $400 = $80 to a charity. Thus, she spent a total of $100 + $50 + $80 = $230. Therefore, Gina kept $400 - $230 = $170.