Question

There are a total of 122 countries in Africa, Europe, and North America (as of 2003). 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 countries?

Answer 1

A + E + N = 122
E = 2N
A = 7 + E....A = 7 + 2N

(7 + 2N) + 2N + N = 122
5N + 7 = 122
5N = 122 - 7
5N = 115
N = 115/5
N = 23 <== North America

E = 2N
E = 2(23)
E = 46 <== Europe

A = 7 + E
A = 7 + 46
A = 53 <=== Africa