Question: Missy had a giant piggy bank in her bedroom. Every day she would search the house for change to put in her bank. After 4 years, the bank was opened and it contained $450 in change. If the second, third, and fourth-year she doubled the amount of money she put in the bank from the amount she had put in the previous year, how much money, in dollars, did she put in the bank the first year?
Answer with step-by-step thinking: We let x be the amount of money she put in the bank the first year,. Then the second year was 2 * x,. and the third year was 2 * 2 * x = 4 * x,. and the fourth year was 2 * 2 * 2 * x = 8 * x. And the total amount she put in the bank, $450, is the sum of all four years, or $450 = x + (2 * x) + (4 * x) + (8 * x). This simplifies to $450 = 15 * x. And therefore, the amount of money she put in the bank the first year was x = $30.
So the answer is 30.


Question: Reggie's father gave him $48. Reggie bought 5 books, each of which cost $2. How much money does Reggie have left?
Answer with step-by-step thinking: The cost of the books is 5 × $2 = $10. Reggie has $48 − $10 = $38 left.
So the answer is 38.


Question: When Spencer jumps rope, he jumps 4 times per minute. He jumps for 10 minutes each session and does 2 sessions each day. How many jumps will Spencer do in 5 days?
Answer with step-by-step thinking:
In 1 session he jumps 4 times / minute * 10 minutes = 40 times. In 5 days he does 2 sessions / day * 5 days = 10 sessions. He jumps 10 sessions * 40 times / session = 400 times in 5 days.
So the answer is 400.