this type of question can be confusing.
Basically, you know that you have isolated 50% of the 150mg pure product, so it is 75mg pure. the remaining is also 75mg, and of the 75h, since they are in racemic form so there is another 25% of the desire product. Adding up the two percentages gives you 75% which is about 112mg.
Reply to this when you have further questions. Thanks.
