They were La Paz, Bolivia -- Dar Es Salaam, Tanzania -- New Delhi, India -- and Sydney, Australia.

Petrol seller in Bangalore, India: www.flickr.com/photos/mattlogelin

We asked reporters to check local gas prices. First up, Ruxandra Guidi in Bolivia...

Listen to all of the reports

So -- among the four cities we visited -- the price of gasoline was highest in Tanzania's capital -- at 5 dollars and 6 cents a gallon.

Which makes Dar Es Salaam the answer to our Geo Quiz today.