Hey, you are lucky !  They just did a part of the work for you.

Look into the first equation: they just expressed x via y in it.

So, they made our work easier.

Substitute the expression x = 5y + 3 from the first equation to the second one. You will get a single equation for y:

2*(5y+3) + 4y = -1.

Simplify and solve it for "y":

10y + 6 + 4y = -1  --->  14y = -1 -6  --->  14y = -7  --->  y =  = -0.5.

Now substitute this valu of "y" into the very first equation and get

x = 5y + 3 = 5*(-0.5) + 3 = -2.5 + 3 = 0.5.


Answer.  x= 0.5,  y= -0.5.