00:01
So if we're going to add these two fractions, we need a common denominator.
00:05
To do that, we're going to find the least common multiple between 4 and 5.
00:13
So a least common multiple is the smallest number that both of these numbers can multiply to that they have in common.
00:22
For example, with 4 and 5, our number is 20.
00:26
That is the smallest number that 4 can go into and 5 can go into.
00:32
So what we're going to do is transform each of these fractions so that they have a denominator of 20.
00:38
We do this by multiplying them.
00:42
So 4 times 5 will make the denominator 20, and if we were going to multiply the bottom by 5, we also have to multiply the top by 5.
00:51
5 times 4 will make the denominator 20, and we have to multiply the top by 4 as well.
00:56
It always has to be the same...