Mara and Riley went to a carnival, Mara rode the bumper car two times, Riley rode the space shuttle four times, and they both rode the Ferris wheel three times. If a ticket for a bumper car cost $2, a ticket for a space shuttle cost $4, and a ticket for a Ferris wheel cost $5, how much money did they spend?
Let's think: Mara spent $2 x 2 = $4 for riding the bumper car two times. Riley spent $4 x 4 = $16 for riding the space shuttle 4 times. They spent $5 x 3 = $15 each riding the Ferris wheel 3 times. So, they spent a total of $15 x 2 = $30 riding the Ferris wheel. Therefore the total amount they spent at the carnival is $4 + $16 + $30 = $50.. The answer is: 50.

The middle school sold 6 more than two times the number of fair tickets as it did tickets to the baseball game. If 25 fair tickets were sold, how many baseball game tickets did the school sell?
Let's think: Two times the number of fair tickets is 25 * 2 = 50 tickets. 50 + 6 = 56 tickets.. The answer is: 56.

Jack went to a supermarket with $100 and bought 4 bottles of water. Then his mother called him and asked him to buy twice as many bottles as he already bought. Each bottle cost $2. Finally, he also bought half a pound of cheese and 1 pound of cheese costs $10. How much money does Jack have remaining?
Let's think: Jack's mother asked him to buy 2 * 4 = 8 bottles of water. Thus Jack bought 4 + 8 = 12 bottles of water in total. Altogether, the bottles of water cost 12 * $2 = $24. The cheese cost 1 / 2 * $10 = $5. So Jack spent $24 + $5 = $29 on water and cheese. Since he started with $100, he now has $100 - $29 = $71 left.. The answer is: 71.

If one fourth of the engines are defective, and there are 5 batches of 80 engines each. How many engines are not defective?
Let's think:
There are 80 * 5 = 400 engines in total. 400 / 4 = 100 of the engines are defective. 400 - 100 = 300 of the engines are not defective.. The answer is: 300.