boeing737

Just on the last two questions of my physics homework, and I really don't understand them! They're topics we haven't covered yet, the teacher just said have a go at them but I really don't understand them. 1, A barge of total mass 300kg is pulled by a single rope attached to a tugboat of mass 1000kg. If the drag on the tug and the barge is one-tenth of their respective weights, and the total forward force exerted bt the tug is 5130kg force, find the magnitude of: a, the total force resisting the forward motion of the tug and barge (is this just 30kg + 100kg?) b, the acceleration of the tug/barge system c, the unbalanced accelerating force on the barge ? d, the tention in the towing rope ? 2, An astronaut of mass M1 = 80kg stands on the horizontal floor of a spaceship moving vertically with acceleration a. If the acceleration due to gravity on the astronaut is g = 9.81 ms^-2, write a mathematical expression for and calculate the value of the reaction force R between the astronaut and the floor of the spaceship when: a, a=0 b, a=8 ms^-2 upwards c, a=8ms^-2 downwards. I really don't understand, especially the last question? Please could someone explain these to me. I spent ages on the rest of the homework trying to get it right, but these questions just tripped me up. Please help!