Diana had chocolate, and ate some, leaving 0.75 of it for Sarah.
Sarah ate 18.5 grams of it and return the rest to Diana, which was 65% of the original chococate.
How much chocolate did Diana have at the beginning?
and the solution is:
0.75x-18.50=0.65x
0.75x-0.65x=18.500.1x=18.50x=185
So Diana had 185 grams of chocolate. Hoped that helped!!!