The x-intercept, is the x-value when the function "cuts" the x-axis, when y = 0. To find the x-intercept we just need to evaluate the function at y = 0.
[tex]\begin{gathered} 6x-4\cdot0=21 \\ \Rightarrow x=\frac{21}{6}=\frac{7}{3} \end{gathered}[/tex]The y-intercept follows the same idea, then, we just need to evaluate the function at x = 0.
[tex]6\cdot0-4y=21\Rightarrow y=-\frac{21}{4}[/tex]Then, our intercepts are:
[tex]\begin{gathered} x-\text{intercept}=\frac{7}{3} \\ y-\text{intercept}=-\frac{21}{4} \end{gathered}[/tex]