A cell phone company has a monthly plan of $40 plus $0.45 for any minutes used over 700. Before receiving his statement, John saw he was charged a total of $48.10. Write and solve an equation to determine how many minutes he must have used during the month. Write an equation without using decimals.
Answers
Step-by-step explanation:
The formula for determining the cost of the cell phone bill (when more than base number of minutes is used) is
c
=
p
+
(
m
−
b
)
r
Where:
c
is the total cost of the bill: $48.10 for this problem.
p
is the base price of the plan: $40 for this problem.
m
is the number of minutes used: what we are solving for in this problem.
b
is the base number of minutes allowed: 700 for this problem.
r
is the rate for additional minutes: $0.45 for this problem.
Substituting and solving for
m
gives:
$
48.10
=
$
40.00
+
(
m
−
700
)
$
0.45
$
48.10
−
$
40
=
$
40.00
−
$
40
+
(
m
−
700
)
$
0.45
$
8.10
=
0
+
(
m
−
700
)
$
0.45
$
8.10
=
(
m
−
700
)
$
0.45
$
8.10
=
(
$
0.45
×
m
)
−
(
$
0.45
×
700
)
$
8.10
=
$
0.45
m
−
$
315.00
$
8.10
+
$
315.00
=
$
0.45
m
−
$
315.00
+
$
315.00
$
323.10
=
$
0.45
m
−
0
$
323.10
=
$
0.45
m
$
323.10
$
0.45
=
$
0.45
m
$
0.45
$
323.10
$
0.45
=
$
0.45
m
$
0.45
323.10
0.45
=
m
718
=
m
m
=
718
John used 718 total minutes during the month,