SOLUTION: Patricia Burgess knows that at some point during the calender year her basic monthly telephone rate increased from $17.10 to $18.40. If she paid a total of $207.80 for basic teleph

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Question 471335: Patricia Burgess knows that at some point during the calender year her basic monthly telephone rate increased from $17.10 to $18.40. If she paid a total of $207.80 for basic telephone service for the calender year, in what month did the rate increase take effect
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
during the calender year her basic monthly telephone rate increased from $17.10 to $18.40.
If she paid a total of $207.80 for basic telephone service for the calender year, in what month did the rate increase take effect
:
Let m = no. months she paid $17.10
then
(12-m) = no. of months she paid $18.40
:
17.10m + 18.40(12-m) = 207.80
17.10m + 220.80 - 18.40m = 207.80
17.10m - 18.40m = 207.80 - 220.80
-1.30m = -13
m = %28-13%29%2F%28-1.3%29
m = +10 months at the lower rate, then the increase took effect in the 11th month (Nov)
:
:
see if that's true
10(17.10) + 2(18.40) =
171.00 + 36.80 = 207.80