Question

David rented a car for his family vacation. The total bill for the car was $622. The standard rate for one week is $400. The rate for an additional day is $37. How many additional days did David have the car?

Answer 1

David had the car for 6 additional days.

Explanation:

Let total price be t = $622

Let one week price be w = $400

Let additional day price be d = $37

To get the number of additional days (let it be x) we need to subtract the weekly price from the total price, so getting the price for all the additional days, and then divide it by the rate of the additional days, so we get to number of days.

The equation should look like this:

x = (t - w) / d

x = ($622 - $400) / $37

x = $222 / $37

x = 6

We can also get to the equation from the other side, how the total price is calculated: total price is weekly price plus additional daily rate times additional days.

t = w + xd we need to reorder to x, so we subtract w from both sides

t - w = xd. to get x we need to divide both sides by d, so d must not be 0

(t - w) / d = x

Note: we know that d is greater than zero, because the final price was greater than the weekly price, so there must have been additional days.