Two hydrated compounds are first weighed, then heated so that water of crystallisation is removed. The resulting anhydrous compounds are weighed, and the measurements are listed below. $3.97\,\text{g FeSO}_4\cdot x\text{H}_2\text{O}$ produces $2.17\,\text{g}$ of anhydrous $\text{FeSO}_4$. $2.88\,\text{g CaSO}_4\cdot y\text{H}_2\text{O}$ produces $2.27\,\text{g}$ of anhydrous $\text{CaSO}_4$. What are the values of $x$ and $y$? $[M_r: \text{FeSO}_4, 152; \text{CaSO}_4, 136; \text{H}_2\text{O}, 18]$
- A$x = 5, y = 2$
- B$x = 5, y = 5$
- C$x = 7, y = 5$
- D$x = 7, y = 2$