Find the probability of the missing outcome

Question

There are three choices of soda, - Coke, Sprite and Dr. Pepper. The probability of getting a coke is 3/10 and the probability of getting sprite is 1/5. Find the probability of getting Dr. Pepper.

Answer 1

3/10 + 1/5 + x = 1

3/10 + 2/10 + x = 1

1/2 + x = 1

x = 1/2 or 5/10