Zack only has dimes and nickels in his car. He has 21 coins that value $1.50. How many dimes and how many nickels does he have in his car.

Question

Using substitution 

Answer 1

Let x be number of nickels

Let y be number of dimes

 

Therefore:

 

x + y = 21    (Total number of coins)

 

Also:

 

.05x + .10y = 1.50      (Total value of coins)

 

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Solve the first equation for x:

 

y = 21 - x

 

and then substitute it in the second equation:

 

.05x + .10(21 - x) = 1.50

 

Now solve this equation for x to get the number of nickels.  Then from that you can easily determine the number of dimes.  Can you finish off the problem?  Please let us know what you get for your final answer.