
If a cup of cereal has 12 grams of fiber, which is 40% of the recommended daily allowance, then recommended daily allowance x grams of fiber is 100%.
Write a proportion:
[tex]\dfrac{12}{x}=\dfrac{40}{100},\\ \\x=\dfrac{12\cdot 100}{40}=30\ grams[/tex]
Answer: the recommemnded daily amount of fiber is 30 grams.