Question: Jacob takes four tests in his physics class and earns 85, 79, 92 and 84. What must he earn on his fifth and final test to have an overall average of 85?
Answer: Since wants needs an 85 as an average and he takes five tests, he must have 85 * 5 = 425 total points. Currently he has 85 + 79 + 92 + 84 = 340 points. So for his fifth test he needs 425 - 340 = 85 points. The answer is 85.

Question: Dany owns a farm, in his farm he has 4 cows and 3 sheep that eat 2 bushels a day. He also has 7 chickens that eat 3 bushels a day. How many bushels should he have to suffice the animals for a day?
Answer: Dany has to have 4 x 2 = 8 bushels a day for the cows. He has to have 3 x 2 = 6 bushels a day for the sheep. And he also has to have 7 x 3 = 21 bushels a day for the chickens. Therefore, Dany has to have 8 + 6 + 21 = 35 bushels to suffice the animals for a day. The answer is 35.

Question: John had $20. He spent 1/5 of his money on snacks and 3/4 of the remaining money on necessities. How much is left of John's money?
Answer: John spent $20 x 1 / 5 = $4 on snacks. He had $20 - $4 = $16 remaining. He spent $16 x 3 / 4 = $12 on his necessities. So, John is left with $16 - $12 = $4. The answer is 4.

Question: Bobby needed to make some trips with his truck and had only 12 gallons of gasoline. He drives to a supermarket 5 miles away and then drives back home. Then he headed to his farm which was 6 miles away. Two miles into the journey, he turned around and drove back home to retrieve some farming tools he forgot to take earlier and drove down to the farm. If he now has exactly 2 gallons of gasoline left, at what rate in miles per gallon has his truck been consuming gasoline?
Answer:
The trip to the supermarket and back home covers 5 + 5 = 10 miles. The round trip of two miles each before he actually went to the farm covers 2 + 2 = 4 miles. Six miles to the farm and the total mileage is 10 + 4 + 6 = 20 miles. The truck consumed 12 - 2 = 10 gallons of gasoline for the total journey. So, the rate is 20 / 10 = 2 miles per gallon. The answer is 2.