Answer
(a) The cost for a wrong number call is:
Penny Saver \$0.395
Most Minutes \$0.493
USA Card \$0.26
(b) Using USA Card instead of Most Minutes would save \$0.233 on a wrong number call.
Work Step by Step
(a) The cost for a wrong number call is the sum of the connection fee and the cost per minute.
Penny Saver = 0.39 + 0.005 = 0.395
Most Minutes = 0.49 + 0.0025 = 0.493
USA Card = 0.25 + 0.01 = 0.26
(b) Using USA Card instead of Most Minutes would save $0.493 - 0.26 = 0.233$