Each month, a shopkeeper spends 8 x plus 15 dollars on rent and electricity. If she spends 3 x minus 7 dollars on rent, how much does she spend on electricity? Use pencil and paper. For which value (s) of x is the amount the shopkeeper spends on electricity less than $100? Explain how you found the value (s).

Question

Heidy Dunlap

Mathematics

19 May, 07:00

Each month, a shopkeeper spends 8 x plus 15 dollars on rent and electricity. If she spends 3 x minus 7 dollars on rent, how much does she spend on electricity? Use pencil and paper. For which value (s) of x is the amount the shopkeeper spends on electricity less than $100? Explain how you found the value (s).

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Answers (1)

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Rabbit · Answer 1

x < 15.6

Step-by-step explanation:

She spends on rent and electricity

P (x) = 8x + 15

She spends on rent

Q (x) = 3x - 7

She spends on electricity

R (x) = P (x) - Q (x) = (8x + 15) - (3x - 7) = 5x + 22

R (x) = 5x + 22

If R (x) < $ 100 we get

5x + 22 < 100

⇒ 5x < 78

⇒ x < 15.6