algebra
posted by aj .
Joseph always throws change into a can and takes it out every two weeks. This time it is all nickels and dimes. There are six times as many dimes as nickels, and the value of the dimes is $4.95 more than the value of the nickels. How many nickels and dimes does Joseph have. (please help me and please show the solution and equation of the problem. Thank you)

Solve mentally:
Start with 6 dimes and 1 nickel.
The difference is $0.55.
To get $4.95 as the difference, we have to multiply by the factor $4.95/0.55=9
So there are 54 dimes and 9 nickels.
Solve by algebra:
N=number of nickels
D=6N=number of dimes
0.10D0.05N=4.95
0.10(6N)0.05N=4.95
0.55N=4.95
N=4.95/0.55=9 (as before)
D=6*9=54 
John sister has $4.95 in dimes and quarters in her piggy bank. There are 3 fewer dimes than quarters. How many quarters and dimes are in the piggy bank?