How many countries are in each of these three continents?

Question

There are a total of 122 countries in Africa, Europe, and North America. Europe has twice as many countries as North America, and Africa has seven more than Europe. How many countries are in each of these three continents? 

Answer 1

a + w + n = 122

e = 2n

a = e + 7 = 2n + 7

 

n + 2n + 2n + 7 = 122

 

I bet you can solve it from here!