first step: list the possible combinations of coins:
4q, 0d, 1n
...
0q, 0d, 21n
Then note how many cannot change $1.00
4q, 0d, 1n
...
0q, 0d, 21n
Then note how many cannot change $1.00
i mean there is more
but hey, my head hurts
Q D N X = not able to give change
4 0 1 β β = able to give change
3 3 0X
3 2 2β
3 1 4β
3 0 6β
2 5 1β
2 4 3β
2 3 5β
2 2 7β
2 1 9β
2 0 11β
1 8 0X
1 7 2β
1 6 4β
1 5 6β
1 4 8β
1 3 10β
1 2 12β
1 1 14β
1 0 16β
0 10 1β
0 9 3β
0 8 5β
0 7 7β
0 6 9β (haha 69 funny number)
0 5 11β
0 4 13β
0 3 15β
0 2 17β
0 1 19β
0 0 21β
IM GOING TO MY FRIENDS HOUSE TO DO THESE QUESTIONS TOGEHTER AND IM GONNA LOOK STUPID. now i wont so thank youuu