SAT OG, P797/10一道OG上的数学题,帮忙翻译一下.

SAT OG, P797/10一道OG上的数学题,帮忙翻译一下.各位大侠哪位帮忙翻译一下OG上一道数学题啊?原题是：Philip used four pieces of masking tape, each 6 inches long, to put up each of his posters. Philip had a 300 foot rool of masking tape when he started. If no tape was wasted, which of the following represents the number of feet of masking tape that was left on the roll after he put up n posters? (12 inches=1 foot)Answer: 300-2n