Verified Answer :

\(2y+5x-z=4y+6x\ \ \ \ \ \ |subtract\ 4y\ from\ both\ sides\\\\-2y+5x-z=6x\ \ \ \ \ |subtract\ 5x\ from\ both\ sides\\\\-2y-z=x\ \ \ \ \ \ |add\ z\ to\ both\ sides\\\\-2y=x+z\ \ \ \ \ \ |divide\ both\ sides\ by\ (-2)\\\\\boxed{y=-\frac{x+z}{2}}\\\\==============================\\\\8xy=z\ \ \ \ \ \ |divide\ both\ sides\ by\ 8x\\\\\boxed{y=\frac{z}{8x}}\)

2y+5x-z=4y+6x

4y-2y=5x-6x-z

2y=-x-z

y=(-x-z)/2

------------------------

8xy=z

y=z/(8x)