Answer:
Theusage is 585 minutes of call duration..
Step-by-step explanation:
Fixed plan cost is M=$.39.95
Charge for first 500 minutes call: Free
Charge for call exceeding 500 minutes: $.0.35/minutes.
Let x minutes be the total call duration.
The bill is P=$.69.70 i.e. more than $.39.95, which indicates
call duration is more than 500 minutes.
The rule states that bill for call exceeding 500 minutes is
P=M+(x−500).0.35 or
69.70=39.95+(x−500).0.35 or (x−500).0.35=69.70−39.95 or
(x−500).0.35=29.75 or (x−500)=
0.35
29.75
or
(x−500)=85 or x=500+85=585 minutes.
The usage is 585 minutes of call duration .
Step-by-step explanation:
hope this helps