Each of the 15 bricks shown in this diagram has a number. Only five of the numbers are shown. Except for the five bricks in the bottom row, each brick has a number that is the sum of the numbers of the two brinks upon which it rests. For example, if the brick between the '9' and the '2' bricks was 21 (which it is not) then the brick above it to the left would have the number 30 and the brick above it to the right would be 23. What should be the number of the top brick?

The answer is 110 as can be verified from the diagram left.

I received only 4 answers to this problem. Admittedly, a little algebra helps. They were from Andy DeBauch, Richard Birkill, John Stafford and Clem Robertson. John Stafford won the draw. Thanks to all who had a go.