Batho ba le bararo ba ne ba kgaogana madi a $1920. Wa bobedi o tsere $80 go feta wa ntlha mme wa boraro a tsaya gabedi go feta wa bobedi. Bala seabe sa wa ntlha.

There are 26 countries in South America and, in each country, there are 5 cities with 1000 people living in each city.  If the whole population lives in these cities, how many people are there in South America?
A re re X ke madi a a tserweng ke wa ntlha.
Wa bobedi o tsere X+<<+80=80>>80.
Wa boraro o tsere (X+80)*2.
Palogotlhe ya madi X + (X+80) + (X+80)*2 = 1920.
X + X + 80 + 2*X + 80*2 = 1920
X*4 + 240 = 1920.
X*4 = 1680.
X = <<420=420>>420.
#### 420 

Since each country has 5 cities, then in all the 26 countries, there are 26*5 = <<26*5=130>>130 cities.
If each city has 1000 people, then the 130 cities have 130*1000 = 130000
#### 130000