Answer:
D. 405
Step-by-step explanation:
First, you find the area of the swimming pool without the water. That is 9 x 9 = 81. Then you multiply the area (without water) by 5 to find the area with the water.

y = slope (x) + y - intercept
To find the slope we need to find out how much the x's and y's increase or decrease...
To find the y - intercept if any, simply look for coordinates ( 0 , y ) or 0 and a #.
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In this case, as time passes, the water level decreases therefore we have a negative slope.
Time is our x and amount (ft) is our y.
On the x side it increases by 2
On the y side it decreases by 10
Now do y over x ==> 10 over 2 and get 5 ==> m
-5 is our slope and 50 is our y - intercept
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The "rate of change" is another word for slope.
Well, slope is - 5ft is our slope.

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I hope that helps you out!!
Any more questions, please feel free to ask me and I will gladly help you out!!
~Zoey
Pretty sure 40. i think its 40 because 120 divided by 80 is 1.5 which is half. so 80 divided by 2 = 40. not sure tho