[Question]Greta received 10 more letters in the mail than her brother. Greta's mother received twice the total number of letters Greta and her brother received. Calculate the total number of letters the three received if Greta's brother received 40 letters.
[Answer]Since Greta's brother received 40 letters, Greta received 40 + 10 = 50 letters. Together, Greta and her brother received 50 + 40 = 90 letters. Greta's mother received twice the total number of letters Greta and her brother received, which totals 90 * 2 = 180 letters. In total, the three received 90 + 180 = 270 letters. The answer is 270.

[Question]In a yard, the number of tanks is five times the number of trucks. If there are 20 trucks in the yard, calculate the total number of tanks and trucks in the yard.
[Answer]There are 5 * 20 = 100 tanks in the yard. Altogether, there are 100 + 20 = 120 trucks and tanks in the yard. The answer is 140.

[Question]Clive is buying olives for dinner. He has $10 to spend and needs 80 olives. A jar of 20 olives costs $1.50. How much change will Clive have when he buys what he needs?
[Answer]He needs 4 jars of olives because 80 / 20 = 4. He will spend $6 because 4 x 1.5 = 6. He will have $4 in change because 10 - 6 = 4. The answer is 4.

[Question]In preparation for his mountain climbing, Arvin wants to run a total of 20 kilometers in a week. On the first day, he ran 2 kilometers. On each subsequent day, he increased his running distance by 1 kilometer over the previous day. If he runs for 5 days a week, how many kilometers did he run on the 5th day?
[Answer]
On the second day, Arvin ran 2 + 1 = 3 kilometers. On the third day, he ran 3 + 1 = 4 kilometers. On the fourth day, he ran 4 + 1 = 5 kilometers. So on the fifth day, he ran 5 + 1 = 6 kilometers. The answer is 6.