Answer:
There are 12 ways to make change for a $50 bill using $5, $10 and $20 bills
Step-by-step explanation:
Let's write down every possibility starting by using the largest quantity of $20 bills and we'll go from there, everytime that we get a $10 bill we will split it in the next option into 2 $5 bills.
(20)(20)(10)
(20)(20)(5)(5)
(20) (10)(10)(10)
(20)(10)(10)(5)(5)
(20)(10)(5)(5)(5)(5)
(20)(5)(5)(5)(5)(5)(5)
Now we start with the largest quantity of $10 bills (5) and go from there, splitting them into two 5 dollar bills in the next option.
(10)(10)(10)(10)(10)
(10)(10)(10)(10)(5)(5)
(10)(10)(10)(5)(5)(5)(5)
(10)(10)(5)(5)(5)(5)(5)(5)
(10)(5)(5)(5)(5)(5)(5)(5)(5)
(5)(5)(5)(5)(5)(5)(5)(5)(5)(5)
