First, I think what you mean is ratio, not ration.
A ratio can be expressed with a colon. For example, 2 cups of rice to 2 cups of water. The ratio would be 2:2. To convert this to fraction, you just have to simply take the left side of the ratio as the numerator, and the right side as the denominator. In fraction, it would be 2/2. If you want to simplify it, that would just be equal to 1.