Just carpet has eight different quality grades of carpeting. Three types are being selected for a corporate test on durability. how many different samples of size 3 can be taken without replacement? how many different samples of size 5 can be taken without replacement?

When we have a set of N elements, the number of combinations of K elements (such that N ≤ K) from these N elements is:

Then if we have 8 different types of carpet, and we want to see how many different samples of 3 types we can choose, we just need to replace N by 8, and K by 3 in the above equation:

So there are 56 different samples.

Now we can do the same, but this time we want to use 5 types of carpet, then we will have K = 5.

Again, we have 56 different samples.

48 / 6 = x

in this case, x will equal the amount of money in each card!

x therefore will be 8.

trent had $8 in each birthday card.