hasil dari 7 per 8 + 2 1 per 4-1 3 per 5 adalah

= (7/8 + 2 1/4) - 1 3/5
= (7/8 + 9/4) - 8/5
= (7/8 + 18/8) - 8/5
= 25/8 - 8/5
= 125/40 - 16/40
= 109/40
= 2 29/40