What is the answer to 6x 2y 5z-4x 2z-5y?

Answer 1

The "answer" would be a set of three numbers ... the numbers that 'x', 'y', and 'z'

must be in order to make the statements true. In order to find them, you need

three separate equations, because you have three separate unknowns.

Without three separate equations, the only thing you can find is some equations

that describe one unknown in terms of the others, but you can't find unique values

for them.

Even with the missing operators in the question, we're pretty sure that there are

most likely not three "equals" signs there, and that you haven't stated three

separate equations.