Answer: -
37.5 g of NaCl are in 250 g of a 15.0% (by weight) solution.
Explanation: -
Total mass = 250 g
Percentage of NaCl = 15.0 %
= 
Thus
= 
Number of grams of NaCl present = 
= 37.5 g
The amount of sugar is 2621 mg
Why?
The complete question is:
A 12.630 g milk chocolate bar is found to contain 8.315 g of sugar.
Part B. What will be the amount of sugar in milligrams if the size of the milk chocolate bar is reduced from 12.630 g to 4.000 g ?
To find the answer we have to determine first the amount of sugar in milligrams per gram of chocolate bar. We can find that by applying the following conversion factor:

Now, we have to determine the amount of sugar in milligrams if we had a chocolate bar with 4.000 g:

Have a nice day!
<span>0.650 kg... I think,
But what are the answer choices?</span>