Question 235918
You could do that and go on to use elimination to solve the system or you could use substitution (which is what I'm going to use):


{{{x + 7y = 5}}} Start with the first equation.



{{{9-7y + 7y = 5}}} Plug in {{{x= 9-7y }}}. In other words, replace 'x' with 9-7y. Now we can easily solve for 'y' (if there is a solution)


{{{9= 5}}} Combine like terms.


Since the equation is clearly false, this means that we have a contradiction and that there are no solutions to the given system. So the system is inconsistent.