Hi Guest!
Let x be the number of quarters Gisele has. Thus Gisele must have x+16 nickels.
To calculate cents, we can write 25x + 5(x+16) = 590
Simplifying, 25x + 5x + 80 = 590 or 30x = 510
Solving for x, we get x = 17
Gisele has 17 quarters.