Starting with the expression:
![15x-30x](https://img.qammunity.org/2023/formulas/mathematics/college/zfhfiynd6o4xhn6pgg7dmxx5ah1alqx35g.png)
First, notice that both terms have a common factor of x. Therefore, rewrite the expression as:
![15x-30x=x(15-30)](https://img.qammunity.org/2023/formulas/mathematics/college/4f78kfrutyf4y3thcu3qncfe117okohl2x.png)
Next, notice that 30=15*2. Therefore, both 15 and 30 have a common factor of 15. Rewrite the expression again factoring out 15:
![\begin{gathered} x(15-30)=x\lbrack15(1-2)\rbrack \\ =15x(1-2) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/8ldf21axe7wf1crv09aw09wnpixcv7pu72.png)
Since the greatest factor of 1 is 1, then the expression has no further common factors.
Therefore, the greatest common factor is 15x.
![(15x)/(15x)-(30x)/(15x)=1-2](https://img.qammunity.org/2023/formulas/mathematics/college/de2tqgd5rxsxsp1qd1i1jv6lr4f8v6ltv6.png)
The final factored expression would be:
![15x(1-2)](https://img.qammunity.org/2023/formulas/mathematics/college/l45ouzs15szi7yhkpths4909k9gs6k40gs.png)