How many different sums of money can be formed from one $2 bill, three $5 bills, two $10 bills, and one $20 bill?

Question

the answer at the back of the book is 23, but i don't know how to solve it.

Answer 1

We note that the question requires different sums of money, irrespective of how they are made up, it is important not to double count. For example 1-$10 and 2-$5 bills should be counted as one sum.

Start with the multiples, namely the $5, $10, and $20 bills. The possible sums range from $0 to $55 in $5 increments. That makes 12 possible sums.

By adding a $2 bill, we get 12 more sums, namely from $7 to $57 in $5 increments. This makes a total of 24 sums, including $0.

If the question implies at least one bill must be used, then there are 23 sums.

Answer 2

is there a formula for this?

Answer 3

Yes, I believe there is one called the combination formula, search it up.

And yes, I do realise I'm replying to a comment from 2010. Hope it was worth the wait. :)

Answer 4

need help 2

Answer 5

use combination formula