Jacob has exactly 84 cents in his pocket. he only has dimes and quartere. how many pennies does he have if he has 3 dimes

3 dimes
3 times 10=30
30 cents are dimes
84=dimes+quarters
84=30+quarters
minus 30
54=quartesr
that can't be right
quartesr go like this
1 quarter=25
2 quarter=50
3 quarters=75
maybe there are pennies even though a penny is neither a dime nor a quarter

2 quarters make 50
4 pennies make the last 4

I guess 4 pennies