I think you made some errors
In question A you made an error with surface, you filled in 0.150 but it should be 0.150^2 (to get internal surface area widthxheight)
Question B can be solved with strain = elongation = dL/L0 with dL being the difference in lengt and L0 the initial length.
The modulus of elasticity can be solved with: E= Stress/strain
Also you made some errors with the units.
I included a picture of how I did it , hope you can read my writing
Good luck and just let us know if you have questions