Answer:
Your probability of choosing a red marble is 30%
Step-by-step explanation:
You'll need to start by adding all the marble's which will give you 100.
30 + 50 + 20 = 100
Then add up the non-red marbles, which is 70.
50 + 20 = 70
30 red marbles are left.
Now, you'll have the fraction 30 over 100.
As a percentage that would be 30%
