If 2x + y + 3z = 10 ,-3x - 2y + 7z = 5 ,3x + 3y - 4z = 7 , what is the value of x ?	Choose the correct choice from the following answers.
A) 3
B) 6
C) 4
D) 7
E) 8
Explanation:   2x + y + 3z = 10 â€“-------I   -3x - 2y + 7z = 5 â€“------ II   3x + 3y - 4z = 7 -------- III   add II and III   -3x - 2y + 7z =5   3x + 3y - 4z = 7   -------------------------------   0+y+3z = 12â€¦.......... IV   sub (IV)from 1, we get 2X= 8   x = 4   ANSWER: 4
<result>C</result>
If 2x + y + 3z = 10 ,-3x - 2y + 7z = 5 ,3x + 3y - 4z = 7 , what is the value of x ?