Yolanda paid for her movie ticket using 28 coins, all nickels and quarters. The ticket cost $4. Which system of linear equations can be used to find the numberof nickels, n, and the number of quarters, q, Yolanda used?

If nickels and quarters add up to 28 coins then it would be
n + q = 28

If nickels are .05 and quarters are .25 and the total is $4 then it would be
.05n + .25q = 4