Answer:
[tex]20 + 20x \leq 100[/tex]
Step-by-step explanation:
Let x be the number of minutes she can continue, since she's already 20 feet below the ocean surface and is diving at the rate of 20 ft/minute, her depth with respect to x would be
20 + 20x
But she doesn't want to reach more than 100 feet below the surface
[tex]20 + 20x \leq 100[/tex]