Question: Tom swims for 2 hours at a speed of 2 miles per hour. He then runs for half the time at 4 times the speed. How many miles did he cover?
Answer with step-by-step thinking: He swam 2 * 2 = 4 miles. He ran for 2 / 2 = 1 hour. His running speed was 2 * 4 = 8 mph. So he ran 8 * 1 = 8 miles. So his total distance was 8 + 4 = 12 miles.
So the answer is 12.

Question: Jake amasses a fortune of 80 bitcoin. He donates 20 bitcoins to charity. He then gives half of all the bitcoins to his brother. After that, he triples the number of bitcoins he has. Then he donates another 10 coins. How many coins does he have?
Answer with step-by-step thinking: He had 80 - 20 = 60 after the donation. He kept 60 / 2 = 30 after giving half to his brother. So he has 30 * 3 = 90 coins. He then does 1 more donation and has 90 - 10 = 80 coins left.
So the answer is 80.

Question: A family went out to see a movie. The regular ticket costs $9 and the ticket for children is $2 less. They gave the cashier two $20 bills and they received a $1 change. How many children are there if there are 2 adults in the family?
Answer with step-by-step thinking:
They gave the cashier $20 x 2 = $40. Since a $1 change was returned, this means the tickets cost $40 - $1 = $39. Two adult tickets cost $9 x 2 = $18. So, $39 - $18 = $21 was spent for the children's tickets. Each child's ticket costs $9 - $2 = $7. Therefore, there are $21 / $7 = 3 children.
So the answer is 3.