Hi All,
If you don't immediately see an 'elegant' approach to solving this problem, then you can still solve it relatively quickly with some 'brute force' and a bit of arithmetic. From the answer choices, you can see that the total number of coins is no more than 20, so there aren't that many potential calculations that you would have to do to find the exact number of each type of coins that 'fit' this situation.
In basic terms, we're told that a certain number of .09s + a certain number of .14s total 2.06.... There are some Number Property rules that we can use to save some time:
.14 multiplied by an integer will end in an EVEN digit
2.06 ends in an even digit
Since (even) + (even) = (even), .09 multiplied by an integer MUST end in an EVEN digit for the sum to equal 2.06
The number of red tokens MUST be EVEN, so that significantly cuts down the number of options to consider....
IF... we have....
2 red tokens, then the remaining value is $1.88. Can that be evenly divided by .14? Try it... (the answer is NO).
4 red tokens, then the remaining value is $1.70. Can that be evenly divided by .14? Try it... (the answer is NO).
6 red tokens, then the remaining value is $1.52. Can that be evenly divided by .14? Try it... (the answer is NO).
8 red tokens, then the remaining value is $1.34. Can that be evenly divided by .14? Try it... (the answer is NO).
10 red tokens, then the remaining value is $1.16. Can that be evenly divided by .14? Try it... (the answer is NO).
12 red tokens, then the remaining value is $0.98. Can that be evenly divided by .14? Try it... (the answer is YES and the remaining 7 tokens are green).
Thus, the total number of tokens is 12 red + 7 green = 19 total tokens
Final Answer:
GMAT assassins aren't born, they're made,
Rich