If a 2/3 cup serving of cereal provides your full daily value of full look acid than what percent of your daily value of folic acid will you receive in 1/2

Write a proportion like 2/3 is to 100% as 1/2 is to X. ( 2/3:100::1/2:X) 

Multiply the centers and divide by the know side. 100 x 1/2 = 50 and 50 divided by 2/3= 75 

So the answer is 75 % of the daily value. 

Maybe in English you call "centers" and "sides" by other names. But I am translating what I learned in another language.