Mary cried because she got fewer / less toys for Christmas than her sister did.

Wrong
Less / Fewer Grammar Rule
Use less to mean a smaller quantity of something.
Use fewer to mean a smaller number of individual things.
> Mr Smith is a practical man, the less money he makes, the fewer dollars he spends.
Aha! There is room for improvement. In the next weeks you will keep getting similar question to practice.
Remember the above grammar rule and Try again