Answer this question:A library has a collection of 100 historical novels arranged on a shelf. 5 people borrow 2 books each from the shelf on a particular day, and 20 more books are borrowed from the shelf on the second day. How many books are remaining on the shelf after the second day?
Five people borrowed 5 people * 2 books / person = 10 books on the first day. After the second day, the total number of borrowed books increased to 10 books + 20 books = 30 books. The total number of books on the shelf after the second day is 100 books - 30 books = 70 books.
The answer is 70.

Answer this question:A four-layer pyramid is being built with each layer having three times as many sandstone blocks as the layer above it. The top layer is a single block. How many sandstone blocks are in the pyramid?
There are 1 * 3 = 3 blocks in the second layer. There are 3 * 3 = 9 blocks in the third layer. There are 9 * 3 = 27 blocks in the fourth layer. Thus, there are 1 + 3 + 9 + 27 = 40 sandstone blocks in the pyramid.
The answer is 40.

Answer this question:Alex and his friend had a free throw contest. Alex made 8 baskets. Sandra made three times as many baskets as Alex and Hector made two times the number of baskets that Sandra made. How many baskets did they make in total?
Sandra made 3 * 8 = 24 baskets. Hector made 24 * 2 = 48 baskets. In total they made 8 + 24 + 48 = 80 baskets.
The answer is 80.

Answer this question:Jenny had $24 left after spending 3/7 of her money. How much is half of her original amount of money?
Jenny spent 1 - 3 / 7 = 4 / 7 of her money. Since 4 / 7 is equal to $24, then 1 / 7 is equal to $24 / 4 = $6. So, Jenny originally had $6 x 7 = $42. Therefore, half of her original amount of money is $42 / 2 = $21.
The answer is 21.