What fraction is the equivalent of 0.5?

Your 0.5 is 1/2 or 2/4 or 3/6 or 4/8 or, well, you get the picture. The ratio of the numerator to the denominator of the fractional equivalent to 0.5 is 1:2 so as long as you write a fraction with the top number equal to half the bottom number, you're good.