Functions help PLEASE! I BEG OF YOU!?

Question

anonymous · Answer

Amelia is planning the trajectory of her next flight using the altitude & distance from Paris, France. She has determined her function to be f(x)=-4x+102. 
Based on the situation aboce, describe any necessary restrictions to the domain & range. Provide justification for the restrictions.

anonymous · Answer

Oh this one isnt that bad

anonymous · Answer

Readeh for help?

anonymous · Answer

All you need to do is add 4x to the right side and left side taking away the negative 4x and putting a positive on on the other x this will give you 4x squard = 102 square both of them than you will get 4x = 10.09 divide by 4 on both sides and round to nearest 10th and x = 2.5

anonymous · Answer

Thank you!!

anonymous · Answer

but how does that describe any necessary restrictions to the domain & range. Provide justification for the restrictions.

anonymous · Answer

the answer for this is the domain and range are all real numbers it does not make sense to solve a function without a number to plug in?