FERMAT 2020 Problem 15

Suppose that N=3 x+4 y+5 z, where x equals 1 or -1 , and y equals 1 or -1 , and z equals 1 or -1 . How many of the following statements are true?

  • N can equal 0 .
  • N is always odd.
  • N cannot equal 4.
  • N is always even.

Answer Choices
A. 0
B. 1
C. 2
D. 3
E. 4