How to calculate tension in a rope?

[BEECHBOY707]

Homework Statement

The link to the problem is here, sorry I couldn't put the diagram in so thought it was better to link!
I need help with both questions, the attempt is for the first question.
https://www.dropbox.com/s/2stb476hp738w9l/Physics question.jpg

Many thanks for any help!

Homework Equations

Moments clockwise=Moments anticlockwise
F=ma

The Attempt at a Solution

Moments clockwise=Moments anticlockwise
5*15=TD
75=TD
...?
Not sure first bit is right tho!

 

[SteamKing]

In all of these problems, do the standard analysis:

1. Draw a free-body diagram and indicate all known forces and moments applied.
2. Write equations of equilibrium.
3. Solve the equations of equilibrium for the unknown forces and reactions.