Andrea notices that the 40-foot tree next to her is casting a 10-foot shadow. How tall, in inches, is Andrea if she is casting a 15-inch shadow at the same time?
(height of tree) / (shadow of tree) = (Andrea's height) / (Andrea's shadow)
Convert everything to inches beforehand.
(40 * 12)/(10 * 12) = x/15
x = 60 inches