Lucy has decided to start a dog sitting business. She needed 45 dollars in supplies to get her new venture started. She charges 2 dollars for each dog she walks for 20 minutes.
Write a linear equation that shows how much money she should expect to make. (Note: The 45 dollars used for supplies takes away from the income of charging 2 dollars per dog walked. Use the fixed costs as - 45 instead if + 45.)
a) y = 2x + 45
b) y = -2x + 45
c) y = -2x - 45
d) y = 2x - 45
This assumes that y represents the money earned and that x represents how many "20min" she has walked. 2x represents the amount she earns every 20min, so we should subtract 45 from that to get y=2x-45. That corresponds to answer choice (d).