Question

If a barrel is 1/3 full and then you add 8 gallons to it to make it 3/5ths full, how much does the entire barrel contain?

Answer 1

make same denoms
1/3 times 5/5=5/15
3/5 times 3/3=9/15

so the question is
5/15 plus 8 gallons=9/15
it take 8 gallons to get from 5 to 9 so
9-5=4
4 units=8 gallons
dividee 4
1unit=2 gallons

entire baralle is 15 units
2*15=30

entire is 30gallons