If 2x+3y+z=55,x-y=4 and y - x + z=12,then what are the values of x , y and z?

If 2x+3y+z=55,x-y=4 and y - x + z=12,then what are the values of x , y and z?

Quiz

Answer/Solution

7,11,8

Steps/Work

The given equations are:
2x+3y+z=55 …(i); x + z - y=4 …(ii); y -x + z =12 …(iii)
Subtracting (ii) from (i), we get: x+4y=51 …(iv)
Subtracting (iii) from (i), we get: 3x+2y=43 …(v)
Multiplying (v) by 2 and subtracting (iv) from it, we get: 5x=35 or x=7.
Putting x=7 in (iv), we get: 4y=44 or y=11.
Putting x=7,y=11 in (i), we get: z=8.
Answer is E.