The number of property sales in a region this year is expected to be 3...

This problem uses function notation to describe a multiplicative relationship. The input x is the number of properties sold last year, and the output H(x) is the expected number sold this year. Since this year’s sales are 3 times last year’s sales, the function rule is H(x)=3x. The given input is 280 because 280 properties were sold last year. Substituting gives H(280)=3(280)=840. That means 840 property sales are expected this year. The answer choice must show the correct input of 280 and the correct output of 840. The other options either reverse the values or use an incorrect output. Therefore, the correct answer is C.

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