Step 2:
![10x-30=7x](https://img.qammunity.org/2023/formulas/mathematics/college/r1u0hzovdpefebznwk9qzp71obtc506n0t.png)
Step 3: To balance an equation using the same mathematical operation on both sides. In the given case to get all terms with variable x on one side of the equation you use the subtraction property: subtract 7x in both sides of the equation:
![\begin{gathered} 10x-7x-30=7x-7x \\ \\ 3x-30=0 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/kxrcuy5qgd864gqgcejz8kahk35iynwrhr.png)
Answer C) subtraction property