Question

A store charges their customers based on the number of items that they buy. Jane bought four items and was charged $15 and George bought twelve items and was charged $39. Write a function to model the cost based on the number of items you buy. Then determine how much you bought if you were charged $33.

A) f(x) = 3x + 3; f(10) = 33
B) f(x) = 3x + 3; f(33) = 102
C) f(x) =1/3 + 3; f(90) = 33
D) f(x) = 1/3x + 3; f(33) = 14

Answer 1

A)
`f(x) = 3x + 3; f(10) = 33`

Explanation:

`39 = 3x + 3 \\ \\ 36 = 3x \\ \\ 12 = x`

`15 = 3x + 3 \\ \\ 12 = 3x \\ \\ 4 = x`

*
`33 = 3x + 3 \\ \\ 30 = 3x \\ \\ 10 = x`

** From what the problem said, we know that we selected the correct equation.

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