G. o is going on a hike in the mountains on a hot summer day. he has 4/5 gallon of water that he split into 4 bottles. what fraction of a gallon is in each bottle

Each bottle has (1/5) gallon

that's so Obvious

Hi there! So, we are talking about Go having 4/5 gallons of water being split into 4 bottles. For this scenario, we have to do division. This involves the fraction 4/5. To divide fractions, all you have to do is keep the first fraction the same, change division into multiplication, and flip the second fraction over by the reciprocal. In other words, flip the numbers over to get the fraction reversed. For example, the reciprocal of 7/4 is 4/7. 
So for this case, 4/5 is our divided, so we keep that the same. We change the division symbol into multiplication, and 4 becomes 1/4. Keep in mind that any whole number has a denominator of 1. The reciprocal of 4 is 1/4. This is our multiplication problem:

4/5 * 1/4

Now, all we have to do is multiply straight across. That means multiply the numerators together and the denominators together. 4 * 1 is 4. 5 * 4 is 20. You get 4/20 or 1/5 in simplest form. There. 1/5 of a gallon is in each bottle.