Ursula is working at a marketing firm. She created a 30-second long commercial. Her boss told her that this commercial is too long to air and told her to shorten the commercial by 30%. How long will this commercial be after Ursula makes the desired changes? Give me reasons, before answering the question
Ursula's boss want's the commercial to be 30 / 100 * 30 = 9 seconds shorter. After Ursula makes the desired changes, the ad is going to be 30 - 9 = 21 seconds long. So the final answer is 21.