I need help with my homework

Question

Mrs. Boyd has a desk full of quarters and nickels. If she has a total of 24 coins with a total face value of $ 2.80 how many of the coins are nickels?

Answer 1

Let x = the number of quarters

Ley y = the number of nickels

x + y = 24     x = 24 - y

.25x + .05y = 2.80      Multiply both sides of this equation by 100 to get rid of the decimal points.

25x + 5y = 280

25(24-y) + 5y = 280

600 - 25y + 5y = 280

-20y = -320

y = 16