give the answers, please

Gemma has a box of red, blue and green pencils. She chooses a pencil at random. The probability that she chooses a red pencil is 0.5 The probability that she chooses a blue pencil is 0.2 (a) What is the probability that Gemma chooses a pencil that is either red or blue? Answer .......... What is the probability that she chooses a green pencil? (c) There were ten pencils in the box originally. How many pencils were green