Three boxes are resting on a surface, as shown below, A 790 N force acts on them. Calculate: (a) the acceleration of the system if u = 0, (b) the acceleration of the system if u = 0.30

Three boxes are testing on a surface, as shown. A 790 N force acts on them. Calculate: 790 N (a) the acceleration of the system if p = 0, 12.01:; (b) the acceleration of the system if p = 0.30 i 55 1'3 951'! ///////// ////