Answer
If w is the wattage of a safe bulb:
$w\leq75$
Work Step by Step
To be safe, the wattage must be 75 or less.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.