math
posted by 5 grade .
this is a math riddle that i can't do so please help i am a fraction eguivalent to 2/4 the sum of my numerator and my denominator is 21 what fraction am i
here it is help me please's

Since the sum is odd, either the numerator or denominator is odd.
Since the fraction is 1/2, the denominator is even. So, we want a faction with odd numerator, even denominator, where they add to 21 and denominator is twice the numerator.
1/2? no
3/6? no
5/10? no
7/14 <<<
or, since the denominator is twice the numerator, that means 3 times the numerator is 21. So, 7/14.