Math Is Fun Forum

Jai Ganesh

Administrator

Registered: 2005-06-28

Posts: 48,413

formula

how do i write a formula for this problem:

The cost of renting a car for a day if the Rental Company charges $20 perday and $0.30 per km driven?

Thanks!!

I am moving this to 'Help Me' Section, Monique.
The formula would be
C=20n+0.3d
where C is the Cost in Dollars, n is the number of days and d, the distance in kilometers.

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It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

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Monique

Member

Registered: 2007-02-17

Posts: 22

Re: formula

You're an absolute God, Ganesh! Thanks!

I have another question:  if a person renting the car has only $100 how far can they drive in a day based on the formula C=20n+0.3d?

by now you can probably tell I know absolutely nothing about maths.

MathsIsFun

Administrator

Registered: 2005-01-21

Posts: 7,713

Re: formula

C = 100, n = 1, so

C=20n+0.3d

becomes

100=20×1+0.3d

Solving:
100 = 20 + 0.3d
100-20 = 20-20 + 0.3d
80 = 0.3d
80/0.3 = (0.3/0.3)d
266.666... = d

Answer 266.666... km

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"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

Monique

Member

Registered: 2007-02-17

Posts: 22

Re: formula

Thankyou so much