Jawabanmu

2014-04-27T15:48:49+07:00
A. resultan gaya : 450-350 = 100 N ke barat
b.percepatan
   F = m . a
   100 = 20 . a
   a = 100 / 20 = 5 m/s^2
2014-04-27T15:49:09+07:00
A.R=F1-F2=450-350=100 N, b.percepatan benda, a=F/m, a=100/20=50m/s^2 arah gerak balok, ke arah barat.