If Mrs. Wong had a whole package of flour (1, or 8/8), and she used 3/8 of it, how much is left over?

Find that answer, and then convert it to a percent. I think that you should memorize the conversion between certain fractions and percents, like fractions with an 8 as the denominator. But if don't have them memorized at the moment, then set up a proportion.

For example, if I want to convert 1/8 to percent, I would write

and solve for x by cross-multiplying:

So 1/8 = 12.5%.

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