It is not possible that she spent $320 for the second purchase, this is because the prices of the books and the video games did not change.
In her first purchase, Marrillia bought 4 books and 3 videos and in her second purchase, she bought double of the products she bought in the first purchase, that is, 8 books and 6 videos. Since there is no price change in the products, Marilla must have spend $360 [$180 * 2] in her second purchase.