[tex]x=2y+1[/tex]
what is [tex]10y-5x[/tex]?
all you gotta do is substitute the value of [tex]x[/tex] in the equation:
[tex]x=2y+1\\10y-5(2y+1)[/tex]
now solve for [tex]y[/tex]:
[tex]10y-5(2y+1)\\10y-10y-5=-5[/tex]
so the value of [tex]10y-5x =[/tex] [tex]\boxed{-5}[/tex]
