Acollection of 54 coins is worth $3.90. the collection contains only nickles and dimes let n represent the number of nickles and let d represent the number of dimes. how many of each type of coin are in the collection

OK. So. we know that there is a total of $3.90
A dime is worth $0.10 and a nickle is worth $0.05
So, yo need to make a simple equation here.
Im not gonna give you the answer, just tell u how to do it. 
Just tell me what you get in the comments. 

So don't take my word i'm not exactly a mathematical person but i would assume a. because while selling the soap every month you increase in sells so you would by 11 percent. the you would get the factor 0.89 which if i had to guess would be the monthly profit over 11 probably wrong tho