RBI Grade B Officers 2011 dec Paper

(1)7x+6y+4z=122...(i)4x+5y+3z=88...(ii)
9x+2y+z=78...(iii)
By equation (iii) × 3 – equation(ii),
27x+6y+3z=234
4x+5y+3z=88
– – – –
________________
23x+y=146...(iv)
By equation (iii) × 4 – equation(i),
36x+8y+4z=312
7x+6y+4z=122
– – – –
_____________
29x+2y=190...(v)
By equation (iv) × 2 – equation(v),
46x+2y=292
29x+2y=190
– – –
______________
17x=102...(iv)
⇒x=6
From equation (iv),
23×6+y=146
⇒y=146–138=8
From equation (iii),
9×6+2×8+z=78
⇒54+16+z=78
⇒z=78–70=8
Clearly, x < y = z