Question 1059580:  Jackie has a jar of dimes and quarters in it. The jar has 6 more quarters than it has dimes. if the value of the coins is 6.40, how many quarters are in the jar? 
 Answer by addingup(3677)      (Show Source): 
You can  put this solution on YOUR website! q = d+6 since she has 6 quarters more than dimes, if you want to make them equal you have to add 6 to the dimes or subtract 6 from the quarters. 
Each quarter is 25 cents, or 0.25 of a dollar (a dollar has 100 cents), we'll call them 0.25q 
Each dime is 10 cents, we'll call them 0.10d 
: 
0.25q+0.10d = 6.40 Above I said that q = d+6. Substitute in this equation: 
0.25(d+6)+0.10d = 6.40 distribute the 0.25, like this: 
0.25d+1.50+0.10d = 6.40 Add d on left and subtract 1.50 on both sides: 
0.35d = 4.90 divide both sides by 0.35 
d = 14 She has 14 dimes and 14+6 = 20 quarters. 
------------------------------------------------ 
Check: 
14*0.10 = 1.40 
20*0.25 = 5 
Total . . 6.40 Correct 
  | 
 
  
 
 |   
 
 |