Problem: If y=2xy=2 xy=2x and z=2yz=2 yz=2y, then x+y+zx+y+zx+y+z equals
Answer Choices:
A. xxx
B. 3x3 x3x
C. 5x5 x5x
D. 7x7 x7x
E. 9x9 x9x Solution:
x+y+z=x+2x+2y=x+2x+4x=7xx+y+z=x+2 x+2 y=x+2 x+4 x=7 xx+y+z=x+2x+2y=x+2x+4x=7x.