A percent mean per 100 so 500% is 500/100 which is 5, and I guess you could use 500/100 and then just divide each by 100 to get the fraction 5/1. so 5.0 as a decimal 5/1 as a fraction
36 feet. how I found this was I divided 5 by 30 to see how many time the house was multiplied in size, it was six. so then you multiply the height with six.