For this, we must take out a greatest common factor. A greatest common factor is a number that both the numerator (Top number) and denominator (Bottom number) share in multiples. By this, I mean that both 4 and 12 can be made by multiplying the number 4 a certain amount of times.
4 goes into 4, 1 time, therefore, the top number can be made into a 1
4 goes 12, 3 times, therefore, the bottom number can be made into a 3
So your answer is:
1/3
I Hope this Helps! Please Feel free to message me with questions on greatest common factors or how I got the answer!
-Sinnamin