Kathy's internet company charges a connection fee of 0.21 cents for each call and 0.06 cents per minute. in february kathy made a total of 50 calls. she was charged 40.50. kathy claims she talked for a total of 250 minutes on her calls made in february. explain why kathy's claim is incorrect.

Let us assume that the number of minutes Cathy called = x
Connection fee for each call that Cathy has to pay = 0.21 cents
Charge per minute that Cathy has to pay = 0.06 cents
Total number of calls made by Cathy in February = 50
Total amount that has been charged to Cathy = $40.50 
Then
(50 * 0.21) + (x * 0.06) = 40.50
10.5 + 0.06x = 40.50
0.06x = 40.50 - 10.50
0.06x = 30
x = 30/.06
   = 500
So from the calculations we come to know that Cathy had made calls for 500 minutes in the month of February. Hence her claim that she called for 250 minutes in completely false or incorrect.