Question

Each​ month, a shopkeeper spends 5x + 17 dollars on rent and electricity. If she spends 3x -4 dollars on​ rent, how much does he 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).

Answer 1

If 5x+17 is rent and electricity combined, and 3x-4 is just rent, then to find electricity, you need to subtract 3x-4 from 5x+17 to get just rent. (5x+17)-(3x-4) = 2x + 21. So he spends 2x +21 dollars on electricity. To find the value of x when the shopkeeper spends less than $100 on electrcity, make the equation for electricity equal 100. 100 = 2x +21, then solve for x. 79 = 2x. x = 39.5 All of the values of x would be under 39.5. x>39.5