Solution:
To pay a bill of Rs. 107, we can use different combinations of Rs. 1, Rs. 10 and Rs. 50 notes.

Let's consider the number of Rs. 50 notes we can use:

- We can use 0, 1 or 2 Rs. 50 notes.
- If we use 2 Rs. 50 notes, we need to pay the remaining Rs. 7 using Rs. 1 and Rs. 10 notes.
- If we use 1 Rs. 50 note, we need to pay the remaining Rs. 57 using Rs. 1 and Rs. 10 notes.
- If we use 0 Rs. 50 note, we need to pay the entire Rs. 107 using Rs. 1 and Rs. 10 notes.

Now, let's consider the number of Rs. 10 notes we can use:

- If we use 2 Rs. 50 notes, we cannot use any Rs. 10 notes as it will exceed the bill amount.
- If we use 1 Rs. 50 note, we can use 0, 1 or 2 Rs. 10 notes to pay the remaining amount.
- If we use 0 Rs. 50 note, we can use 0 to 10 Rs. 10 notes to pay the amount.

Finally, let's consider the number of Rs. 1 notes we can use:

- If we use 2 Rs. 50 notes, we need to use 7 Rs. 1 notes to pay the remaining amount.
- If we use 1 Rs. 50 note and 2 Rs. 10 notes, we need to use 37 Rs. 1 notes to pay the remaining amount.
- If we use 1 Rs. 50 note and 1 Rs. 10 note, we need to use 47 Rs. 1 notes to pay the remaining amount.
- If we use 1 Rs. 50 note and 0 Rs. 10 notes, we need to use 57 Rs. 1 notes to pay the remaining amount.
- If we use 0 Rs. 50 note and 10 Rs. 10 notes, we need to use 47 Rs. 1 notes to pay the remaining amount.
- If we use 0 Rs. 50 note and 9 Rs. 10 notes, we need to use 57 Rs. 1 notes to pay the remaining amount.
- If we use 0 Rs. 50 note and 8 Rs. 10 notes, we need to use 67 Rs. 1 notes to pay the remaining amount.
- If we use 0 Rs. 50 note and 7 Rs. 10 notes, we need to use 77 Rs. 1 notes to pay the remaining amount.
- If we use 0 Rs. 50 note and 6 Rs. 10 notes, we need to use 87 Rs. 1 notes to pay the remaining amount.
- If we use 0 Rs. 50 note and 5 Rs. 10 notes, we need to use 97 Rs. 1 notes to pay the remaining amount.
- If we use 0 Rs. 50 note and 4 Rs. 10 notes, we need to use 107 Rs. 1 notes to pay the remaining amount.
- If we use

We get an idea that only 10 and 50 rupee notes never sum 107 do we have to fix rupee 1 note let's see
rupee 1 = 7 notes then 3 cases
rupee 1 =17 notes then 2 cases
1 rupee's 27 notes then 2 cases
1 rupee's 37 notes then 2 cases
1 rupee's 47 notes then 2 cases
1 rupee's 57 notes then 2 cases
1 rupee's 67 notes then 1 cases
1 rupee's 77 notes then 1 cases
1 rupee's 87 notes then 1 cases
1 rupee's 97 notes then 1 cases
1 rupee's 1077 notes then 1 cases
when we add all cases 3+2+2+2+2+2+1+1+1+1+1= 18 cases