hi ronak ,

as you read this solution make sure that you have HCV in front of you.. i'll be using the same figure ...

the terminology we will be using will be: pulley = 1

                                                          wheel =2          

                    tension in the string between them = T₁

                           tension in the string between pulley and mass = T₂

now writing the force equations assuming that the mass moves downwards, we have :

for the mass : mg - T₂ = ma

for the pulley : T₂r₁ - T₁r₁ = I₁(₁)

for the wheel : T₁r₂ = I₂(₂)

also we have : a = r₁(₁)= r₂(₂)

 here I = moment of inertia , and r are the radius , a is the acceleration.....

so solving these we get

    T₁ = I₂(₂)/r₂ = 6.322 N