1 bowl is 14 grams. If you divide the bowl by 14, you get the amount that contains 1 gram. So 1/14 of the bowl has 1 gram of fat. You are allowed 4 grams, so 4/14 of a bowl. That reduces to 2/7 of a bowl has 4 grams of fat.
Let 'b' be the amount of party mix in one bowl.
Let 'x' be the amount of party mix you can consume.
It's really Less than OR EQUAL TO, but I can't write that here. So don't forget it's less than or equal to.
Your inequality is: x < 2/7b
