Since you we have a parallelogram, we will use the fact that that AB and DC are congruent, so are BC and AD
Thus we get the following system
`2y=5x-1 => 2y-5x=-1`
`y+3=2x+4 => y-2x=1`
Solving by elimination, we need to multiply the second equation by 2 (we can also solve by substitution)
Now we have to plug in x in either of the two equations to get y, I will use the second.
`y-2*3=1 => y=1+6=7`
Thus x=3 and y=7