jessicab11
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PLEASE HELP!!!

William recorded data to determine the relationship between the time usage, x, and the percentage of charge left on his mobile phone, y. He graphed the data and drew the line of best fit. The equation of the line of best fit is y = -10x + 100. About how many hours will it take for the phone lose its charge completely?

about 5 hours
about 10 hours
about 20 hours
about 22 hours
about 24 hours

Respuesta :

musiclover10045
y is usage so set y to 0 and solve for x

y = -10x+100

0 = -10x +100
 subtract 100 from each side:
-100 = -10x

divide both sides by -10

x = -100 / -10

x = 10 hours
Using the equation -10x + 100, then the answer has to be 10 hours.

This is because -10 times 10= -100 and -100+100= 0

By the time he uses his phone for 10 hours the battery level will be at 0%.

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