The flagpole is 20 ft high and casts an 8 foot shadow, the oak tree casts a 12 foot shadow. How tall is the oak tree

Answer: 4.8 ft

To answer this question you need to know how much shadow: actual height ratio. Flagpole is having 8 ft shadow with 20 ft actual height. The ratio should be = 8 ft: 20 ft = 0.4

Then multiply the ratio with the oak tree shadow. The equation would be:

0.4 x 12 ft = 4.8 ft