The dude on top of me is correct
To write the equation you start with the 125 because it is monthly and it doesn't say how often you pay the 75 dollars so the equation would be c(f)=125x+75
RHS
=4x-27/0
=not defined=0
LHS
=x-2x+3x+4/7=2x+4/7=(14x+4)/7= 14x+4.
14x=-4
x=-4/14
X=-2/7