Benjamin went to a bookstore and purchased a variety of books. He bought 5 copies of a sci-fi novel, each priced at $20, 3 copies of a history book priced at $30 each, and 2 copies of a philosophy book for $45 each. What was the total cost of his purchases?

The total cost of Benjamin ' s purchases was $ 1 , 1 5 0 . \n To calculate this , we can start by finding the cost of each type of book separately : \n - 5 copies of the sc i - fi novel : 5 x $ 2 0 = $ 1 0 0 \n - 3 copies of the history book : 3 x $ 3 0 = $ 9 0 \n - 2 copies of the philosophy book : 2 x $ 4 5 = $ 9 0 \n Then we can add up the costs to get the total : \n $ 1 0 0 + $ 9 0 + $ 9 0 = $ 1 , 1 5 0 </s>