Hamid published a book of poems. He sold 35 copies in the first week for $10 per copy. He wanted to increase the price of each book to increase his revenue. He found out that for every 50-cent increase, x, in the price per copy, the average number of books he sold decreased by 2 per week. Assuming that Hamid’s revenue is found by multiplying the book price by the number of copies sold, create an equation (in standard form) to model his revenue.