Question 1154597
p(f given e) = p(e and f) / p(e)
p(f given e) = .4
p(e) = .2
p(f given e) = p(e and f) / p(e) becomes:
.4 = p(e and f) / .2
solve for p(e and f) to get:
p(e and f) = .2 * .4 = .08
that should be your solution.