If `2x+y=15 ,\ \ 2y+z=25` and `2z+x=26` , what is the value of `z` ? (a) 4 (b) 7 (c) 9 (d) 11

If 3x-4y+z=7; 2x-z+3y=19 ; x+2y+2z=24 , then what is the value of z ? (a) 4 (b) 5 (c) 6 (d) 8

If 2x+y=17;y+2z=15 and x+y=9 then what is the value of 4x+3y+z?(a)41 (b) 43(c)45 (d) 55 (e) None of these

If 2x+3y=31,backslash backslash y-z=4 and x+2z=11, then what is the value of x+y+z?( a )12 (b) 13 (c) 15 (d) 16

If (x+y)^2-z^2=4, (y+z)^2-x^2=9, (z+x)^2-y^2=36 , what is/are the value(s) of x+y+z ? (a) 0 (b) +-1 (c) +-3 (d) +-7

If 4 x^(2) + 9y^(2) + z^(2) + 49 = 12 ( x+ y + z) , then what is the value of (4x + 9y - z) ?

If x : y : z = 3 : 4 : 9, then what will be the value of (2x + 3y + z) : (2z + x – 3y)?

If x= (a//b) + (b//a), y= (b//c) + (c//b) and z= (c//a) + (a//c) , then what is the value of xyz - x^(2)- y^(2)- z^(2) ?