Layla has a jar filled with 108 coins. If the jar contains only quarters and nickels and has a value of $15.80, how many nickels are in the jar
52
53
55
56

Question

Layla has a jar filled with 108 coins. If the jar contains only quarters and nickels and has a value of $15.80, how many nickels are in the jar 
52
53
55
56

anonymous · Answer

I thought what I was supposed to do was set up 2 equations so I did x+y=108, .5x+.25y=15.80. Then I thought it would be easier just to multiple the answers by .5 then subtract that from 15.80 and figure out how many quarters there would be and make sure it added up to 108. but .5*52=26 which is already more than 15.80. So I am not sure..

anonymous · Answer

let x be the # of nickels
let y be the # of quarters
you can form two equations, the first for the total number of coins:
$$x +y = 108$$$$x = 108 -y$$
The second for the total amount:
$$(NumNickels) * (ValNickels) + (NumQuarters)*(ValQuarters) = $15.80$$
$$(x)*(0.05)+(y)*($0.25)=$15.80$$

anonymous · Answer

Oh. I see what I did wrong now. Thank you so much! You are amazing!