answer:Otto needs to sharpen 9 knives. The first knife will cost 5.00. The next 3 knives will cost 4.00 each, so a total of 3 * 4.00 = 12.00. There are 9 knives in total, and the first 4 knives have already been accounted for, so there are 9 - 4 = 5 additional knives. Each additional knife will cost 3.00. So, the cost for the additional knives will be 5 * 3.00 = 15.00. The total cost for sharpening all 9 knives will be 5.00 + 12.00 + 15.00 = 32.00. 32 The answer is: 32

answer:Expanding (x+y)^2, we get x^2 + 2xy + y^2 = 45. Using the value of xy, we can rewrite this as x^2 + 2(10) + y^2 = 45. Simplifying further, we have x^2 + y^2 = 25. Now, let's expand (x-y)^2. This gives us x^2 - 2xy + y^2. Using the value of xy, we can rewrite this as x^2 - 2(10) + y^2. Simplifying further, we have x^2 + y^2 - 20. But we know that x^2 + y^2 = 25, so (x-y)^2 = 25 - 20 = boxed{5}. The answer is: 5

answer:Wickham invites 30 people to his party. Half of the guests bring a plus one, so there are 30/2 = 15 plus ones. Including the plus ones, there are a total of 30 + 15 = 45 guests at the party. For each guest, Wickham plans to serve a 3-course meal, so he needs 3 plates per guest. Therefore, he needs 45 guests * 3 plates = 135 plates in total. 135 The answer is: 135

answer:To find the slope of the line, we need to rewrite the equation in slope-intercept form, y=mx+b, where m is the slope. First, let's isolate y on one side of the equation: 3x+5y=20 5y=20-3x y=frac{20-3x}{5} Now we see that the equation is in the form y=mx+b, where m=frac{-3}{5}. Therefore, the slope of the line is boxed{-frac{3}{5}}.The answer is: -frac{3}{5}