Solve the system with the addition method:

{8x7y=158x+4y=92\displaystyle {\left\lbrace\begin{array}{ccc} -{8}{x}-{7}{y}&=&-{15}\\-{8}{x}+{4}{y}&=&-{92}\end{array}\right.}

Answer: ( , )

Enter your answers as integers or as reduced fraction(s) in the form A/B.