The volume expansibility of brass and iron are $\text{54}\times {\text{10}}^{-\text{6}}{\text{K}}^{-1}$ and $\text{36}\times {\text{10}}^{-\text{6}}{\text{K}}^{-1}$  respectively. They are supported between rigid walls. They are heated so that they have the same rise of temperature and there is no bending. If the same thermal stress is developed in them, the ratio of Young’s modulus of brass and iron will be: