[Question]: If I'm 4 times older than Billy currently, and Billy is 4 years old, how old was I when Billy was born?
[Answer]: I would currently be 4 * 4 = 16 years old, since I'm 4 times older than Billy's age of 4. Therefore, in order to find my age at Billy's birth we'd simply subtract Billy's age of 4 from my age, meaning I was 16 - 4 = 12 years old.
So the answer is 12.

[Question]: Jackson wants to start saving for the vacation that he's taking next August, 15 months away. He wants to save $3,000.00. If he gets paid 2 times a month how much money does he need to set aside, per paycheck, to have enough money saved for his vacation?
[Answer]: He has 15 months to save $3,000.00 so that's 3000 / 15 = $200.00 a month. He gets paid twice a month so he needs to save 200 / 2 = $100.00 from each paycheck.
So the answer is 100.

[Question]: A couple with two children, ages 6 and 10 years old, decided to go to an amusement park. The regular ticket costs $109, but children below 12 years old have a $5 discount. If they gave the cashier $500, how much change will they receive?
[Answer]:
The ticket costs 109 - 5 = $104 for each child. So the ticket cost of the two children is 104 x 2 = $208. The couple needs to pay the regular price, so it's 109 x 2 = $218. Thus, the family needs to pay a total of 208 + 218 = $426. Therefore, their change is 500 - 426 = $74.
So the answer is 74.