Energy loss through oven insulation over 7 hours

[owura143]

The temperature in an electric oven is 165°C. The temperature at the outer surface in the kitchen is 55°C. The oven (surface area = 1.6 m2) is insulated with material that has a thickness of 0.023 m and a thermal conductivity of 0.045 J/(sm°C).

a) How much energy is used to operate the oven for 7 hours?

(b) At a price of $0.10 per kilowatt hour for electrical energy, what is the cost of operating the oven?

 

[denverdoc]

Owura, please offer at least an attempt at a solution, or what you know or even if I knew that I could get rest.

 

[owura143]

I solved it