According to its nutritional info, a bag of chips has 250 calories per serving. If a 300g bag has 5 servings, how many grams can you eat if your daily calorie target is 2000 and you have already consumed 1800 calories?
If the total calorie target is 2000 and I have consumed 1800 calories then I have 2000-1800 = 
<gadget id="calculator">2000-1800</gadget>
<output>200</output>
200 calories left to eat.
If each serving of chips has 250 calories and I only have 200 calories left to eat, then I can only eat 200/250 of a serving = 4/5 of a serving.
We also know that a 300g bag of chips has 5 servings, hence each serving has 300g/5 = 
<gadget id="calculator">300/5</gadget>
<output>60</output>
60 grams.
If I can only eat 4/5 of a serving, then I can eat only 60g * 4/5 = 240g/5 = 48 grams.

<result>48</result>