219817868746376626676224663436644637264373627363276372645632663726454632736+764738218746473837643837647373637×111112345555555555567890000987654444444444444432377381994465590348309867488398933429379888388585658474348 Have fun (;

Hi, it will be really easy if you start out by plotting a tree diagram and tracing out the probabilities. Then you simply have to multiply the probabilities of placebo and improvement. 

80% Medication 76% improvement
                                 24% no improvement
|
20%Placebo 62% no improvement
                           38% improvement

Solving for P(placebo and improvement) = .20 x .38 = 0.076 = 7.6%