Call Me Maybe is a cell phone provider that charges by month. The first month of service costs $75.45. The total charges after the second month of service are $95.36; after the third month, it’s $115.27.
Write a y = c + d(x−1) equation to represent this situation. Explain your answer.
y = 75.45 + 19.91(x-1)
This equation represents the situation because the first month of service costs $75.45, and each additional month costs $19.91 more than the previous month. The variable x represents the number of months of service, and the variable y represents the total cost of service.
To represent the given situation, we can use the equation y = c + d(x-1), where y represents the total charges after x months, c is the initial cost, and d is the increase in cost per month.
In this case, the initial cost is $75.45, so we can substitute c = 75.45 in the equation. The increase in cost per month, d, can be calculated using the given information.
The total charges after the second month are $95.36, which means the increase from the initial cost in the first month is $95.36 - $75.45 = $19.91.
Similarly, the increase in cost from the second month to the third month is $115.27 - $95.36 = $19.91.
Since the increase in cost per month is the same in both cases, we can assign d = $19.91 in the equation.
Therefore, the equation y = 75.45 + 19.91(x-1) represents this situation.