hey,I am having trouble finding a proof for a piece of coursework based on pyramids.  
The number on the uppermost row is the total of the two numbers below it. The two numbers on the second row are totals of the two numbers below them (in total 1st row=1 number, 2nd row=2 numbers, 3rd row=3 numbers) If the bottom numbers are 'a', 'b', and 'c', then the top number = a+b+b+c . Is there anyway to prove this? many thanks, eddie