HERE ARE THE ANSWERS TO YOUR PUZZLES :

REALLY HARD 

M+(M-L) x (M x M)+(VI-C-V) x (M x M x M) = 5,049,998,094

MOST CHALLENGING!!!

   M/D= 2

(II x D)+(D x IX)+CX-D= 5,110

REALLY EASY 

M-M+V=5

V+V=10 

I-I+M=1000