Tension problem please help?

Question

A 70 cm, uniform, 60 N shelf is supported horizontally by two vertical wires attached to the sloping ceiling. A very small 30 N tool is placed on the shelf midway between the points where the wires are attached to it.

http://session.masteringphysics.com/problemAsset/1039059/5/YF-11-23.jpg

1) Find the tension in left wire.

2) Find the tension in right wire.

Answer 1

I assume u are more interested in the methodology rather then the exact ans:

assuming the shelf is not attached to anything else

1.) t1 + t2 = 90 N ( t1 is tension in 1st and vice versa)

2.) balance out the torques due to two strings and the two ms acting downwards at any point.

now solve