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Yield = 10 + 2.5*X -0.1*X2 where X is the amount of fertilizer in lbs per acre and yields are bu per acre. What is the yield if 8 lbs of fertilizer are applied? Use one decimal place.

You work for a delivery service. With plan A, you can earn $5 per hour plus $0.75 per delivery. With plan B, you can earn $7 per hour plus $0.25 per delivery. How many deliveries must you make per hour to earn the same amount with either plan?

A shop owner is ordering vases from a stock catalogue. Red vases cost $4.20 and clear vases cost $5.70. If 25 vases cost $120, how many of each type of vase did she buy? Also show the algebraic expression.