what is 2y-5x=8... you have to solve for y or x.. Its called system of equasions. It's pre algebra and after solving for x or y you need to graph.

Usually , when you have two unknowns ,
you need to have two equations.

By hit and miss you can actually find the
answer to your problem.
It is not technically algebra.

2y-5x = 8

Try y = 9 and
Try x = 2

2*9 - 5*2 = 8
It works!

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2y-5x = 8

Try y = 14 and
Try x = 4

2*14 - 5*4 = 8
It works!

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As you can see there are many answers that
would fulfill the one equation.