Really can't figure out this system of equations.
The problem states:

"In a game, Theodore received a handful of coins (pennies, nickels, dimes, and quarters) as a prize. When he got home, he found that he had managed to get $2.09 in change. He noticed that he had three times as many pennies as dimes, one more nickel than dimes, and twice as many quarters as dimes. How many quarters did Theodore get in his prize?"

A direct answer would be nice but I am really just looking for help.

Theses are the equations that I have found from the problem (each coin has its first letter as its variable):
3d=p
d+1=n
3d=q

Can't seem to figure out where to go from here.