The houses in the "historic district" of a particular town are either historically protected or not. The above table partially represents these homes and whether they have foundations made from
poured concrete, mortar and field stone, or a combination of both. If only 4.5% of the non-
historically-protected homes have a field stone and mortar foundation, how many homes is this?
Round to the nearest whole number.

It depends on the subject for me. some exams are easier than others so i usually go through it and answer questions i know based on my general knowledge, then double check after. going through the lesson can a lot  because the exams can be  very lesson-specific, but sometimes they are ridiculously long so a lot of people don't take the time. i did find that, when i went through the lessons, i was making 100's on my exams vs strictly using + the internet and  i make 90's. 

The answer is 46,637.5