Hi I'm unable to solve this questions:

7- Darren and Charles are friends who often go to the cinema together. On such visits there is a probability of 0.4 that Darren will buy popcorn. The probability that Charles will buy popcorn is 0.7 if Darren buys popcorn and 0.35 if he doesn't.

When Darren and Charles visit the cinema together:

(a) Find the probability that both buy popcorn

(b) Show that the probability that neither buys popcorn is 0.39 (c) Find the probability that exactly one of them buys popcorn

Sarah sometimes join Darren and Charles on their cinema visits. On these occasions, the probability that sarah buys popcorn is 0.55 if both of charles and darren buy popcorn and 0.25 if exactly one of darren and charles buys popcorn.

When Darren, Sarah and Charles visit Cinema together:

(d) What is the probability that the three of them buy popcorn. (e) charles and sarah buy popcorn but Daren doesn't