Lizzy: Otto's local kitchen supply store charges $5.00 for the first knife that you need sharpened. They charge $4.00 for the next 3 knives and $3.00 for any knife after that. If Otto has 9 knives that need to be sharpened, how much will it cost to sharpen his knives?.
Me: Hmmm, let me think. I think this is the detailed solution:
Knives 2, 3 & 4 will cost $4.00 each to sharpen so that's 3 * 4 = $12.00. Knives 5 - 9 will cost $3.00 each to sharpen so that's 5 * 3 = $15.00. The first knife will cost $5.00, the next 3 cost $12.00 and the rest cost $15.00 for a total of 5 + 12 + 15 = $32.00. Final answer: 32.