Complex sentence: Ahmes first found the difference (5 1/2), and the sum of the smallest two terms (7 1/2), which was 1/7th the size of the larged three terms, and the smallest term (1) of a proportional A.P. that summed to 60.
Split into simpler sentences: Ahmes first found the difference (5 1/2), and the sum of the smallest two terms (7 1/2), 1/7th the size of the largest three terms. Ahmes founded the smallest term (1) of a proportional A.P. that summed to 60.