Answer:
Think about it in terms of division
Explanation:
if comparing 1/5 with 3/5 both are divided by like terms if you add them you have a total of 4/5 or four parts of a whole, if you were to compare the denominator, you would end up with 4/10. Thinking in terms of a pie for instance: adding 1 slice to your other 3 slices on your plate leaves one slice behind so you took 4 out of the five, the size of the pie doesn't change (the denominator)