percent word problem

Question

One machine has a capability of producing 750 pieces per 8-hour shift. It is operating at 80% of its capability. The second machine has a capability of producing 900 pieces per 8-hour shift. It is operating at 75% of its capability. Find the total number of pieces produced per hour with both machines operating. 

Answer 1

(750(0.8) + 900(0.75))/8 = (600 + 675)/8 = 1275/8 = 159.375