Answer:
Step-by-step explanation:
Let be "x" the height inches (in the model) of a 84 foot building.
According to the information provided in the exercise, we know that the height of a two-story building is 21 feet and in the scale model its height is 3 inches.
Knowing this, we can set up the following proportion:
The final step is to solve for "x" in order to calculate its value. We get that this is:
Therefore, an 84 foot building will be 12 inches tall in the model.