A bag contains five red marbles, fifteen black marbles, and ten white marbles. You pick one without looking. What is the probability that the marble will be either red or white

Step-by-step explanation:

5 red

15 black

10 white

altogether the is 30 marbles so that means it is 'out of'  30

and because the is 5 red it would be 5/30

and because the is 10 white it would be 10/30

that should be the answer but if you have to work the total all together then it would be 15/30

hope this helps :)