Answer:
work accomplished = 300*30
= 9,000 J
applied work = 9,000 + 2,000 = 11,000 Joules
efficiency = 100 * work accomplished/work applied
= (9/11)100 = 81.8 %
force applied = (300/6)/.818
= 61.1 N
assuming that the 6 in your question refers to mechanical advantage