Lee really wants a cell phone but wonders if it is too expensive. He decides to get

the cheapest plan that costs $27.50 per month. He has 150 minutes free. Additional

minutes are 35¢ each. He ends up using the phone way more than he expected. He

ends up using 400 minutes in total. How much extra does Lee have to pay?

Answer:The extra amount that he paid is $87.5

Step-by-step explanation:

The plan that Lee got costs $27.50 per month. He has 150 minutes free. Additional minutes are 35¢ each. Converting 35¢ to dollars, it becomes 35/100 = $0.35

Let x represent the total number of minutes that Lee used. Let y represent the total cost of using x minutes. Therefore,

y = 27.50 + 0.3535 (x - 150)

He ends up using the phone way more than he expected. He

ends up using 400 minutes in total. The total cost of using 400 minutes will be

y = 27.50 + 0.35 (400 - 150) = 27.50 + 87.5 = $115

The extra amount that he paid is

0.35 (400 - 150) = $87.5