1. Let's convert 124 centimeters (the height of the young girl) and 93 centimeters (the length of her shadow).
2. We know that 1 meter=100 centimeters, then:
 124/100=1.24 meters
 93/100=0.93 meters
 3. If the girl has a height of 1.24 meters and casts a shadow with 0.93 meters long, what height ("x") will we obtain with a shadow of 13.50 meters long?
 1.24 m-----0.93 m
     x-----13.5 m
 x=(13.5 m)(1.24 m)/0.93 m
 x=18.0 m
 How tall is the tree? The answer is: 18.0 meters
