6)
Given:
[tex]\frac{12x}{3}[/tex]
12 can be factorsied as 2 x 2 x 3.
Hence,
[tex]\begin{gathered} \frac{12x}{3}=\frac{2\times2\times3x}{3} \\ \end{gathered}[/tex]
Cancel out the common factor 3 in the denominator and the numerator of RHS of above equation.
[tex]\begin{gathered} \frac{12x}{3}=2\times2x \\ =4x \end{gathered}[/tex]
Therefore, the simplified expression is 4x.
