I dont understand what they refer to when they say what 128 is 74% of what number.

==> 128 is 100% of 128.

==> 128 is 200% of 64.

==> 128 is 50% of 256.

==> 128 is 10% of 1,280.

Now, what number is it 74% of?

Here's how to find it:

Call the mystery number ' M '.

The question says that 128 is 74% of ' M '.

You know that 74% means 0.74.

And you know that in math, "of" usually means "times".

So you can write the question as

128 = 0.74 times M

128 = 0.74 M

Divide each side by 0.74 : 128 / 0.74 = M

172.973 = M

There's the mystery number. 128 is (about) 74% of 172.973.