What is the probability that a randomly selected movie was given positive comments about both plot and acting?

Question

 Assume that the critic finds that 50 percent of the movies have positive comments about the plot, 30 percent have positive comments about the acting, and 35 percent were not given positive comments about either plot or acting.

What is the probability that a randomly selected movie was given positive comments about both plot and acting? 

Answer 1

35 % had no positive comments

So 100 - 35% = 65% had positive comments about plot or acting or both

If x had positive comments about both then 50 + (30-x) = 65, giving x = 15. (Draw a Venn diagram)

So 15% is the answer