Q$7.$ Let A be the set of students at your school and B the set of books in the school library. Let R$1$ and R$2$ be the relations consisting of all ordered pairs $(a,b),$ where student a is required to read book $b$ in a course, and where student a has read book b$,$ respectively. Describe the ordered pairs in each of these relations.

a$)$ R$1$ R$2$

b$)$ R$1$ R$2$

c$)R1o+R2$

d$)R1-R2$

$e,$