William blackstone was important because he

William Blackstone was a jurist who was the first man to make a commentary on the English Laws. This book of his was known as "The Commentaries on the Law of England." His books were known to target men who did not have an understanding of law jargon which is why he used very easy to understand phrases. He also wrote quite extreme opinions of his views on the law. Aside from that, he was also known to have written a commentary on the Magna Carta as well. Many revolutionary movement leaders cited this man as a source or reference. 

1190 is your answer! the way you get it is 1400 - 15% =1190 : )