This is a nice puzzle from the Scottish Mathematical Council (SMC) Senior Mathematical Challenge of 2008. It is more a logic puzzle than a geometric one.
“In the diagram, each question mark represents one of six consecutive whole numbers. The sum of the numbers in the triangle is 39, the sum of those in the square is 46 and the sum of those in the circle is 85. What are the six numbers?”
See the Shared Spaces Puzzle