solving word problems

If there is 5.5 mcg Vitamin B in 0.66 Cups Granola, and I need to decrease my daily intake by 2.9 mcg, how much less granola do I need to eat?

You can set up a proportion

x/2.9 = .66/5.5

x=.66*2.9/5.5

x=0.348

You need to eat 0.348 cups less granola