Question

Mikes movie Rentals Charge $3.00 for each rental plus $0.50 for each additional day. Reed's Rentals Charge $1.50 each rental plus $1.25 for each additional day. For what number of additional days will the bill at both stores be the same

Answer 1

2

Explanation:

What we need here is to express both charges trough equations, and then find out for which value these equations are equal.

Let X be the amount of additional days of rent.

So, Mikes Movie Rentals cost equations is:

CostMike = 3 + 0.5X

This implies that if there is no additional day (X=0), the cost is $3, if there is one additional day the cost is $3.5, for 2 days $4, and so on ...

Now lets find Reed's Rental cost.:

CostReed = 1.5 + 1.25X

And the interpretation is analogous to the one above. If there is no additional day, Reed's charge is $1.5, for 1 days $2.75, for 2 days $4

(Notice that with the examples I made about interpreting the equations I found out that for 2 days the cost of both is the same. Now lets find it analytically)

For finding the additional days that give the same costs we need to equal both equations:

3 + 0.5 X = 1.5 + 1.25 X

Lets subtract 1.5 from both sides:

3 - 1.5 + 0.5 X = 1.5 - 1.5 + 1.25 X

1.5 + 0.5 X = 1.25 X

Now subtract 0.5 X in both sides:

1.5 + 0.5 X - 0.5 X = 1.25 X - 0.5 X

1.5 = 0.75 X

Dividing both sides by 0.75:

1.5 / 0.75 = 0.75 X / 0.75

2 = X

So, for 2 additional days bith charges are equal.