The answer is 7/12. You get the minimum common multiplo. That is to say a number that is divisible between 3 and 4. Which is 12. Then you divide the twelve between the four and multiply it by the numerator that in this case is one, then it is twelve between four gives three and one three more and you do the same with the three, twelve between three is four by one four plus three. And it gives you the result 7/12