Tim is choosing between two cell phone plans that offer the same amount of free minutes. Cingular's plan charges $39.99 per month with additional minutes costing $0.45. Verizon's plan costs $44.99 with additional minutes at $0.40. How many additional minutes, a, will it take for the two plans to cost the same?

It will take 100 additional minutes for the two plans to cost the same.

Step-by-step explanation:

Tim is choosing between two cell phone plans, Cingular and Verizon. They offer the same amount of free minutes.

Cingular's plan charges $39.99 per month with additional minutes costing $0.45.

Verizon's plan costs $44.99 with additional minutes at $0.40

Let a = the number of additional units that it will take the two plans to cost the same.

This means total cost of Cingular's plan additional minutes will be 0.45a and total cost of Verizon's plan additional minutes will be 0.4a

For the two plans to cost the same,

39.99 + 0.45a = 44.99 + 0.4a

0.45a - 0.4a = 44.99 - 39.99

0.05a = 5

a = 5/0.05 = 100