Whats the problem?
756/35=21,6
First calculate his gross salary after his 401k contributions:

Then find the amount of taxes withheld:

5,760 dollars went towards taxes.
Answer:
B. Both functions are increasing, but function f is increasing faster.
By the law of cosines, the angle

satisfies

which reduces to

which converts to approximately 77 degrees (this can be done my multiplying by 180 and dividing by pi).