A box contains 12 red marbles, 15 black marbles and 18 green marbles. One marble is picked up from the box randomly. What is the probability of getting a red or a black marble?

Respuesta :

I believe the answer is 27/45, or 60%.
12 + 15 + 18 = 45 marbles in total 
12 + 15 = 27 red/black marbles 
[tex] \frac{27}{45} [/tex] is the probability 
Also 60%
Hope this helped :)