In a class of 40 students, everyone has either a pierced nose or a pierced ear. the professor asks everyone with a pierced nose to raise his or her hand. eight hands go up. then the professor asked everyone with a pierced ear to do likewise. this time there are 37 hands raised. how many students have piercings both on their ears and their noses?

for many centuries there were important factors which the economies of the muslim empires developed increasingly. they applied economic procedures in production, investment, finance, taxation and property. they used to tax certain goods (for example: harvest), they charged interest on money lent, they signed contracts with merchants; they relied on a common currency, and they used checks as well as promissory notes. with the money collected by means of taxation, the government provided the needy with an income. in addition, trading networks covered huge distances, so far regions started to have contact and exchange goods. this trade network covered areas of asia, africa and europe.

answer; protectionism fosters competition and keeps price regulated;