Start on the left and work to the right. There are two alternating sequences of letters - one starts with A and moves through the alphabet 5 letters at a time. The other starts on H and moves through the alphabet 3 letters at a time.

Working from top to bottom, replace each letter with its numerical value and read each pair of numbers as a 2 digit number. Numbers follow the sequence of multiples of 9, from 27 to 72.

Start at the top, and work through the triangle in horizontal rows, from top to bottom, left to right. Letters move through the alphabet 5 letters at a time.