Paula had 7 times as many nickels as quarters. their value was 1.80. how many of each coin did she have

nickels = n = 5 cents

quarters = q = 25 cents

5n + 25 q = 180

7q = n

substitute in the first equation

5(7q) + 25q = 180

35q + 25q = 180

60q = 180

q = 3

n = 7q = 7 * 3 =21

# of nickels = 21

# of quarters = 3