Question: Elsa gets 500 MB of cell phone data each month. If she spends 300 MB watching Youtube and 2/5 of what's left on Facebook, how many MB of data does she have left?
Answer with step-by-step thinking: First subtract the 300 MB Elsa spent on YouTube: 500 MB - 300 MB = 200 MB. Then multiply 200 MB by 2 / 5th to find out how much data Elsa spent on Facebook: 200 MB * 2 / 5 = 80 MB. Finally, subtract the data Elsa spent on Facebook from the 200 MB: 200 MB - 80 MB = 120 MB.
So the answer is 120.

Question: Each year a store decreased the price of a certain model of TV by $35. If the price in 2001 was $1950, what was the price in 2009?
Answer with step-by-step thinking: The period the store had the TV was 2009 - 2001 = 8 years. The TV decreased by $35 / year * 8 years = $280. So the price in 2009 was $1950 - $280 = $1670.
So the answer is 1670.

Question: 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?
Answer with step-by-step thinking:
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 answer is 21.