Ihave 3 countries (germany, usa, china) with 3 statistics (people per square km, internet users per 100 people, cell phone owners per 100 people). what i don't get: use mathematical strategies i. e. ratios to compare countries. how do i do that. !

Alright, so if we wanted to take, for example, cell phone owners per 100 people and compare Germany to the USA, we can start by making up a number for Germany - 80 - and a number for the USA - 70. Next, the ratio of people using cell phones is 80/70=8/7 with the numerator being the people from Germany and the denominator being the number from the USA.