Answer:The extra amount that he paid is $87.5
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