6. A Two-story building measures 21 root from the ground. A scale model shows the
building to be 3 inches fall. How many inches
would an 84 foot bullding be in the model?

12 inches

So, we are going to let "x" be the height inches (in the model) of a 84 foot building.

According to the information that was given 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:  

3/21 = x/84

The final step is to solve for "x" in order to calculate its value. We get that this is:    3/21 =x/84

(84) (3/21) = x

So , an 84 foot building will be 12 inches tall in the model.

(when I do the "3/21 it doesn't mean divide it's a fraction"

answer: i think it is (1,-2)