Answer
P(placebo and headache went away within 45 minutes) $=\frac{28}{125}=0.224$
Work Step by Step
The sample space: 150+100=250 women in the study. So, N(S) = 250.
According to the cell in the second row, first column: N(placebo and headache went away within 45 minutes) = 56.
P(placebo and headache went away within 45 minutes) =
$\frac{N(\text{placebo and headache went away within 45 minutes})}{N(S)}=\frac{56}{250}=\frac{28}{125}=0.224$
