Question 1169800
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<pre>

Let x be the number of the 20c coins.

Then the number of the $1 coins is 2x, and the number of the 50c coins is (36-x-2x) = 36-3x.


From the condition, you have this equation

    50*(36-3x) = 20x + 440   cents.


Solve it

    1800 - 150x = 20x + 440

    1800 - 440  = 20x + 150x

       1360     = 170x
 
         x      = {{{1360/170}}} = 8.


Thus the number of the 20c coins is 8.


Hence, the number of the $1 coins is twice as many, i.e. 16.    <U>ANSWER</U>
</pre>

The problem is easily solved using one single unknown and one single equation.