Please help! Hurry!!

D

Step-by-step explanation:

I see you already got other answers but I'm going to offer a more in depth explanation to help with similar questions in the future.

The equation you have here is in the form of y = mx + b

You may have seen this in one of your lessons, maybe refered to as slope, y-intercept form?

We have y = -6x + 640

If we break it down we can see how this is in y = mx + b form.

y is the ounces of water in a water cooler

x is the number of paper cups filled

-6 is our m

and 640 is our b

The question is asking about 640 (our b) so I will talk about that first.

This is the y-intercept, the point where, if we were to graph this (see attachment, green dot on the line), that the line would cross the y-axis. This is the point where x is zero.

In our case this would be the amount of water in the cooler when we have filled zero paper cups with water. Hence the answer being D.

Now I will explain the m value, -6 in this case.

This is the rate of change (or slope).

For this question it is how much water we take out (negative value) per paper cup. In other words, how much water goes into each paper cup, -6 ounces.

Take a look at the second attachment. You can see that I go 6 hops down and 1 hop right (yellow line). This is because we always view our m value as a fraction.

In this case, because we have -6, it appears to not be a fraction but a whole number. Always remember that any whole number is just a fraction over 1. We can rewrite our -6 as -6/1.

Slope is written as rise/run. This means that we rise (vertical, up & down) by our top (numerator) value (in this case go down 6, because the 6 is negative) and run (horizontal, left & right) by our bottom (denominator) value (in this case go right 1, because the 1 is positive).

***Remember: positive rise, go up; negative rise, go down. Positive run go up; negative run go down.

Hope this will help you in the future!