Question 939585
1 nickle = 0.05 dollars
1 quarter  =0.25 dollars
let x be the no of nickles
let y be the no of quarters
total no of coins  =50
  x+y = 50..............eq(1)
 total worth = $ 6.50
   x*0.05+y*0.25 = $6.50 ..............eq(2)
*[invoke linear_substitution "x", "y", 1, 1, 50, 0.05, 0.25, 6.50]
Result : 
   no of quarters  = 20