The graph below represents c, the amount a phone company charges, based on m, the number of minutes the customer uses each month. if there are a maximum of 44,640 minutes in a month, which equation best represents the phone company’s charges? mc011-1.jpg

The y-intercept of the graph shows that at m = 0, c = 15. We can see a constant slope that causes the graph to pass through m = 20, c = 20, as well as m = 40, c = 25. This shows a constant increase of $5/20 minutes, or a slope of 5/20 = 1/4. Based on slope-intercept form y = mx+b, the equation would be c = (1/4)m+15, from 0 <= m <= 44,640. This is the second of the given choices.

The price decreased by 40 percent㏒㏒㏒㏒㏒㏒㏒㏒㏒㏒㏒㏒㏒∞㏒∞㏑⊕⊆⊂ф