An ordered pair (x,y) is a solution to a system of equations if it makes all the equations true. Let's check whether (–1, 5) makes the equations true. Plugging –1 in the first equation for x and 5 in for y, we get –1 + 5 = 4: TRUE Plugging –1 in the second equation for x and 5 in for y, we get –1 – 5 = –6: TRUE
Since it makes both the equations true, it's a solution to the system of equations. So the answer choice is D, the 4th one.