Question 818561
Two formulas for Y in your system; equate then and you have one equation in just the variable, x.  Each equation is already solved for Y in terms of just x.

4x-1=Y, so substitute for Y from the second equation.
4x-1=2x-5;
4x-1-2x=-5
2x-1=-5
2x=-5+1
2x=-4
x=-2


Now use either equation to get the value for Y.