Question 212812
 9x + 4y = -55 ------ eq (i) 
-7x +  y =  51 ------ eq (ii)


Solve eq (ii) for y ------> -7x + y = 51 becomes y = 7x + 51


Substitute 7x + 51 for y in eq (i) 9x + 4y = -55 becomes


9x + 4(7x + 51) = -55


9x + 28x + 204 = -55


37x = -259


{{{x = (-259)/37 = - 7}}}


Substitute - 7 for x in eq (ii) -7x +  y =  51 becomes


-7(-7) + y = 51


49 + y = 51


y  =  2


Therefore, the solution set is ({{{highlight_green(-7)}}},{{{highlight_green(2)}}})