D. Plug the first number into “n” to get the second number
64.50-.10=64.40
64.40-47=17.4
(my way of working math when i'm not in school is weird, but still accurate)
17.4/4=4.35.
It's average change per day is -4.35.
It has infinitely many solutions....because all real numbers satisfy the equation.
Good luck mate :P
Here you go!!! I hope this helps!!! Have a merry Christmas!!