SOLUTION: At the car wash there is a flat fee for the first 8 minutes. Sally was there for 12 mins and cost her $5. John was there for 17 mins and cost him $6.25. Write a equation and find t

Question 456897: At the car wash there is a flat fee for the first 8 minutes. Sally was there for 12 mins and cost her $5. John was there for 17 mins and cost him $6.25. Write a equation and find the cost of the flat fee and cost per minute.
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
At the car wash there is a flat fee for the first 8 minutes.
Sally was there for 12 mins and cost her $5.
John was there for 17 mins and cost him $6.25.
Write a equation and find the cost of the flat fee and cost per minute.
:
Let f = flat fee for the 1st 8 min
Let a = cost for each additional min
:
Two equations:
:
"Sally was there for 12 mins and cost her $5."
a(12-8) + f = $5
4a + f = $5
:
" John was there for 17 mins and cost him $6.25."
a(17-8) + f = $6.25
9a + f = 6.25
:
We can use elimination here, subtract the 1st equation from the 2nd
9a + f = 6.25
4a + f = 5.00
-----------------subtraction eliminates f find a
5a = 1.25
a =
a = .25 for each additional min
:
Find f using the 1st equation
4(.25) + f = 5
1.00 + f = 5
f = 5 - 1
f = $4 is the flat fee for the 1st 8 min
:
Check our solutions in the 2nd equation
9(.25) + 4.00 = 6.25

RELATED QUESTIONS
A car wash charges a flat rate for the first 8 minutes of washing time and also charges a (answered by ankor@dixie-net.com)

a car wash charges a flat rate for the first 8 minutes of washing time and also charges a (answered by rwm)

A car wash charges a flat rate for the first 8 minutes of washing time and also charges a (answered by ankor@dixie-net.com)

A car wash charges a flat rate for the first 8 minutes of washing time and also charges a (answered by josmiceli)

there were 12 packages total, split between small flat-rate boxes for Php 5 each and... (answered by solver91311)

Katherine D'Ann is planning to finance her college education by selling Programs at the... (answered by blairbear252)

Average Senior high school annual cost of tuition fee for all private schools last year... (answered by Boreal)

For a total of 8 hours, Tan rode her motorcycle down a freeway at 55 kilometersperhour.... (answered by ikleyn)

A family has three options for a child's birthday: Adventure Plex, Bright Child, and... (answered by josmiceli)