$\begin{array}{1 1} (a)\; \text{Shoe no. 9 and no. of students is 100 } \\ (b)\; \text{Shoe no. 7 and no. of students is 800} \\ (c)\; \text{Shoe no. 10 and no. of students is 500} \\ (d)\; \text{Shoe no. 4 and no. of students is 500} \end{array}$