How do you express x as a percentage of y?

Let us instead ask: "What is x as a fraction of y"

Q: what is 1 as a fraction of 2?

A: 1/2

So, 1 is a half of 2.

Q: what is 3 as a fraction of 4?

A: 3/4

So, 3 is three-quarters of 4.

Now, a percentage is just the fraction with a denominator of 100.

Let's ask the same questions again.

Q: what is 1 as a fraction of 2?

1/2 = 50/100 = 0.50 - multiplying by 100, we get 50%

Q: what is 3 as a fraction of 4?

3/4 = 75/100 = 0.75 - multiplying by 100, we get 75%

Q: what is x as a percentage of y?

A:

x/y X 100