Jawabanmu

2014-02-28T06:31:15+07:00
W = F x s
90 = (f1 + f2 + f3) x s
90 = (30 + (-40) + f3) x 6
90/6 = ((-10) + f3)
15 = ((-10) + f3)
15 + 10 = f3
25 = f3

2014-02-28T10:48:53+07:00