Question

Carlos has 4/5​​​​ of a tank of fuel in his car. He uses 1/10 of a tank per day.

How many days will his fuel last?

Answer 1

Ok, so 4/5 is also 8/10.  So if he uses 1/10 per day, that means his fuel will last 8 days.

Answer 2

8 days, because 4/5 multiplied by 2 equals 8/10.