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Ashley is driving to Phoenix. Suppose that the remaining distance to drive (in miles) is a linear function of her driving time(in minutes). When graphed, the function gives a line with a slope of -0.85. See the figure below.Ashley has 49 miles remaining after 38 minutes of driving. How many miles were remaining after 22 minutes of driving?

User Arun SS
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1 Answer

22 votes
22 votes

The given graph gives a linear relationship between the driving time 'x' and the remaining distance 'y'.

Since the relationship is linear with slope -0.85, its equation is given by,


y=-0.85x+c

Here 'c' is the y-intercept.

At x=38, the value is y=49,


\begin{gathered} 49=-0.85(38)+c \\ 49=-32.3+c \\ c=49+32.3 \\ c=81.3 \end{gathered}

Substitute the value in the equation,


y=-0.85x+81.3

Now, solve for 'y' when the value of 'x' is 22,


\begin{gathered} y=-0.85(22)+81.3 \\ y=-18.7+81.3 \\ y=62.6 \end{gathered}

Thus, 62.6 miles were remaining after 22 minutes of driving.

User Paddyd
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