Question

One serving of oatmeal provides 16% of the fiber you need daily. You must get the remaining 21 grams of fiber from other sources. How many grams of fiber should you consume daily?

Answer 1

You should consume 25 grams of fiber daily.

The oatmeal represents 16% of the fiber.
The rest of the fiber (21 grams) is 84%.

If 21 grams = 84%, then 1 gram = 4%.
If 1 gram = 4%, then 25 grams = 100%.