MY Very LAST math problem! Can Anyone Assist? Assistance Please
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MY Very LAST math problem! Can Anyone Assist? Assistance Please

[From: ] [author: ] [Date: 12-03-17] [Hit: ]
72:c - 33m = 24.72Well do that to the next set of data as well:62 minutes left $20.08 in credit:c - 62m = 20.08Now we have two unknowns and two equations. Ill solve this by substituion.Ill set both equations to c in terms of m,......

We're told over two months how many minutes of calls in that month, with how much credit was left. we can use that to build a system of equations.

33 min of calls left $24.72. Since we don't know what the starting credit was, we'll start there, then subtract 33 times the amount per minute, which gives us 24.72:

c - 33m = 24.72

We'll do that to the next set of data as well: 62 minutes left $20.08 in credit:

c - 62m = 20.08

Now we have two unknowns and two equations. I'll solve this by substituion. I'll set both equations to c in terms of m, then set the m terms equal to each other since they are both equal to the same "c". Then solve for m:

c - 33m = 24.72
c = 24.72 + 33m

c - 62m = 20.08
c = 20.08 + 62m

set them equal to each other and solve for m:

24.72 + 33m = 20.08 + 62m
4.64 = 29m
0.16 = m

So each minute costs 16 cents. Now we can solve for c:

c = 20.08 + 62m
c = 20.08 + 62(0.16)
c = 20.08 + 9.92
c = 30

Now we know they start with $30 in credit.

Now we can solve the final question: How much credit remains after 70 min of calls:

c - 70m = x

We know c and m. we can plug those in and solve for x:

30 - 70(0.16) = x
30 - 11.2 = x
x = 18.8

There will be $18.80 left in credit after 70 minutes.

-
Subtract 62 mins - 33 mins = 29 mins

Subtract $24.72 - $20.08 = $4.64

Figure out what 1 min of call cost by dividing $4.64 / 29 mins = .16 per 1 min

Subtract 70 mins - 62 mins = 8 mins

Multiply .16 per 1 min x 8 mins = $18.80

Answer is with 70 mins of calls the remaining credit will be $18.80
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