Question 1164328
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Let's say we had a tank that was 30 gallons in total capacity. 
I'm picking on 30 because it is the LCD of the fractions 1/10 and 2/3
Note: 1/10 = 0.10 = 10%


If the tank is 2/3 full, then (2/3)*30 = 20 gallons of gas is in the tank
Then 10% of that amount (20 gallons) is taken out, meaning we take out 0.10*20 = 2 gallons of gas. We then have 20-2 = 18 gallons left.


The amount of empty space is 30-18 = 12 gallons


The fraction of empty space is 12/30 = (6*2)/(6*5) = 2/5


<font size=4 color=red>Answer: 2/5</font>


The tutor @josgarithmetic has the right idea, but somehow got the 2/5 and 3/5 mixed up I think. 
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