The answer is 10 hope it helps SORRY IF I’M WRONG
So to find the ratio of the actual house to the house in the picture you would divide 72/4 to get 18. this means that the ratio is 18:1. Now multiply 2.5 x18 to get the real life height of the house. 2.5x18=45.
So the house is 45 feet tall.
Please anyone correct me if I'm wrong but I think this is right.

Since we need to solve for r we have to leave that variable alone in one side of the equation. We notice that at is adding in the right side, then it goes to the left side substracting, that is:

Therefore:

in the last part we only switch the sides of the equation.