Answer:
5/12
Since demoninators aren't the same we have to find a number that both numbers can divide into, which will be 84
5/84 & 4/84
Now whatever we do to the top we do to the bottom and so on. So how many times did it take those numbers to reach 84?
5/12 took 7 times to reach 84 so it will now be 5x7 like how we times 12 7 times to reach 84: 35/84
It took a shorter time for 4/21 to reach 84 as it only took 4 times so we times 4 by 4 and we get 16/84
Now let's compare: 16/84 or 35/84? We can see the bigger one is the second one, which was originally 5/12 and that's how you get the answer!
Hoped that helped
