Thread:HMcCoy/@comment-28838092-20140825225626/@comment-24808864-20140826221737

Subtract the third equation from the first equation.

(3x+4y)-(4y-3z)=(15-9)

3x-3z=6

x-z=2

Using this new equation, and the second one from your problem (2x-5z=-3) you should be able to use the standard ideas for solving equations (substitution/elimination) to solve the system.