We can go about this 2 ways - YOU can choose which way you find easier.
Way 1 ) Align each fraction next to each other and see what numbers go into each numerator and denominator - I'll show you what I mean :)
10/50 4/20
2 can go into each number, so you'd find out how many times 2 goes into the numerators and denominators, then reduce it little by little.
5/25 2/10
You keep repeating this process, but not with 2! You'd get a wrong answer! You constantly change numbers. And the same numbers are not used for both fractions all the time.
1/5 1/5
Would you look at that! Your fractions WERE equivalent after all! But, if you'd like, you can use Way 2 below
Way 2 )
Divide each numerator by their denominator - I'll show you how
10 ÷ 50 = 0.2, or, 20%
4 ÷ 20 = 0.2, or, 20% also.
Look! Each answer is equivalent!
Now, this way is the way I like to do it, because it has fewer steps and is so easy! I hope this was very useful to you and I hope this helps! :D