Joanna has a total of 50 coins in her purse. The coins are either nickels or quarters. The total value of the coins is $7.10.

Which system of equations can be used to determine the number of nickels, n, and quarters, q, that Joanna has in her purse?

A. n+q+50
0.05n+0.25q=7.10


B. n+q=7.10
50n+50q=7.10

C. 0.05n+0.25q=50
n+q=7.10

D. 0.05n+ 0.25q= 7.10
50n+50q=7.10