Question

For what number of DVDs would the total cost of buying the DVDs without a club membership equal the total cost of joining the club and buying the DVDs with a club membership?

(More information in a second)

Answer 1

So this is an open response question, it's a little harder to ask for help, so...
Info given- Each DVD costs $16
To buy a membership it's $40, and from then on the DVDs for members are only $12
a) What's the total cost of buying 5 DVDs at the store? $80
b) Write an equation that represents y, the total cost of buying x DVDs at the video store. y = 16x
c) What's the total cost of joining the club and buying 5 DVDs? $100
d) Write an equation that represents y, the total cost to a club member, including the membership fee to join and buying x DVDs. y=40 + 12x

Answer 2

ok where are you stuck?

Answer 3

This one
For what number of DVDs would the total cost of buying the DVDs without a club membership equal the total cost of joining the club and buying the DVDs with a club membership?

Answer 4

Would I do the 16x = 40 + 12x thing?

Answer 5

The total cost to buy x DVDs with no membership is y = 16x

The total cost to buy x DVDs with membership is y = 12x+40

so this means...

y = 12x + 40 ... start with second equation

16x = 12x + 40 ... plug in y = 16x

now solve for x

Answer 6

yes exactly

Answer 7

you're allowed to this because you want to know how many DVDs (x) you can buy for both to make the cost (y) equal, so basically x and y are the same in each equation in this case

Answer 8

16x = 12x + 40
4x = 40
x = 10?

Answer 9

good

Answer 10

so you're done

optionally you can find the equal cost, but they just want the number of DVDs

Answer 11

Thank you!

Answer 12

you're welcome