Table$2$B

Q$9$ Paste the screenshot of the balanced system

Q$10$ What is the mass of the mystery object A$?$

${\displaystyle \underset{\text{T}\text{w}\text{o}\text{u}\text{n}\text{t}\text{e}\text{r}-\text{c}\text{l}\text{o}\text{c}\text{k}\text{w}\text{r}\text{s}\text{e}}{\overset{?}{}}}={\displaystyle \underset{?}{\overset{?}{}}}$ Tclockwise