Assuming the thickness of the bracket as t
Area of cross section A= b*t = 0.04*t
Direct stress Sd= P/A 
Bending stress Sb=(M*c)/I
	where c=w+ t/2 i.e., 0.05+ t/2
	M=P*t/2
	I=(b*(t^3))/12

Maximum tensile stress:
	S=Sb+Sd
	S=(P/A)+((M*c)/I)

On simplifying above equation,
	we get
	 (S*b)t^2 - (4P)t - 6Pw = 0
	30=(500/t)+(155*(100+t) / t^2

Standardizing the dimension, we get t=111.5 mm

The corresponding stress induced is 30.00 MN/m^2