For this case we must solve the following inequality:
[tex]5x-10 \leq20[/tex]
Adding 10 to both sides of the inequality:
[tex]5x-10 + 10 \leq20 + 10\\5x \leq30[/tex]
Dividing between 5 on both sides of the inequality:
[tex]\ \frac {5x} {5} \leq \frac {30} {5}\\x \leq6[/tex]
Thus, the function is defined for all values of "x" less than or equal to 6
Answer:
(-∞, 6]
Option C
