We can see that [tex] a [/tex] lies just before 0, [tex] b [/tex] lies between 2 and 3m and [tex] c [/tex] lies between 4 and 5. So, we have
[tex] -1 < a < 0,\quad 2 < b < 3,\quad 4 < c < 5 [/tex]
In particular, this implies that
[tex] -1+4 < a+c < 0+5 \iff 3 < a+c < 5 [/tex]
So, the correct order would be
[tex] -2,\ b,\ a+c [/tex]
