I roll a pair of dice What is the probability that a the sum

I roll a pair of dice. What is the probability that:

a.) the sum of the pips on the top faces is 5 or doubles is rolled?

b.) the sum of the pips on the top faces is 8 or double is rolled?

c.) the sum of the pips on the top faces is 5 or the sum of the pips on the top faces is 8?

d.) the sum of the pips on the top faces is 8 and doubles is rolled?