Suppose that a household's monthly water bill (in dollars) is a linear function of the amount of water the household uses (in hundreds of cubic feet, HCF). When graphed, the function gives a line with a slope of 1.45
If the monthly cost for 21 HCF is $29.53 , what is the monthly cost for 17 HCF?

Question

Suppose that a household's monthly water bill (in dollars) is a linear function of the amount of water the household uses (in hundreds of cubic feet, HCF). When graphed, the function gives a line with a slope of  1.45
If the monthly cost for 21 HCF is $29.53 , what is the monthly cost for 17 HCF?

anonymous · Answer

attachment

anonymous · Answer

@wio Could you help me with this one as well?

anonymous · Answer

Okay so how much does it cost for 21 HCF without any fixed cost?

anonymous · Answer

$29.53 @wio

anonymous · Answer

That is with fixed cost included.

anonymous · Answer

@wio then i'm not sure :/

anonymous · Answer

Though, I'm a bit confused, it says the slope is 1.45

anonymous · Answer

there is a diagram that I posted @wio

anonymous · Answer

Yet 21 * 1.45 is too high

anonymous · Answer

Maybe it should be  $21\times 0.145$

anonymous · Answer

The first thing we need to do is determine the equation of blue line. 
We are given a point on this line as indicated in the graph:

anonymous · Answer

and we are told the slope of this line is m= 1.45

anonymous · Answer

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