Slope = change in y

             change in x

I drew the pictures above by hand because I was unable to insert a picture from the internet on Geogebra.com

Below I have some information that might be useful.

To begin with, I wrote an equation.

y = w times x + b

If b = 0 we have y = w times x

w = slope

y = height of building

x = length of the shadow

So, we can write our equation as y = -0.875 times x and we can use it for calculating any shadows or building heights.

For example, shadow = 20 m

y = 20 times 0.875 = 17.5 m

Because the sun is moving, this wouldn't be an everyday logical situation. :)