You can put this solution on YOUR website! i believe you mean permutations which is an ordered arrangement.
a combination is an unordered arrangement.
the number of combinations would be 1.
the number of permutations would be 3! = 3*2*1 = 6
only 1 combination because each set has to be unique without regard to order of the elements within that set. the sets of NDQ and DQN are considered to be the same set because the order of the elements within the set don't matter and both sets have the elements DQN.
6 permutations because each set can have the same elements but in a different order.
let N = 5 cent coin.
let D = 10 cent coin.
let Q = 25 cent coin.
number of possible combinations is 1 which is equal to NDQ.
number of possible permutations are:
NDQ
NQD
DNQ
DQN
QND
QDN
