Few questions on force & friction-Explanation needed!!!TC Help.?

i can only help with question 1. On the incline we have gravity acting in 2-D,left and downwards so we have to resolve it into its components,20Cos240 degrees is -10N horizontal component. 20Sin240 degrees is -17.32N. There is no vertical acceleration so gravity force equals normal force. Friction equals coefficent of friction*normal force. 0.7*17.32 equals 12.12N. Your friction is 12.12N