Adding x and 19 to both sides of 2y−x=−19 gives x = 2y + 19. Then, substituting 2y+19 for x in 3x+4y=−23 gives 3(2y+19)+4y=−23 . This last equation is equivalent to 10y+57=−23 .Solving 10y+57=−23 gives y=−8 . Finally, substituting −8for y in 2y−x=−19 gives 2(−8)−x=−19 , or x=3 . Therefore, the solution (x, y) to the given system of equations is (3,−8) .
Choices A, C, and D are incorrect because when the given values of x and y are substituted in 2y−x=−19 , the value of the left side of the equation does not equal −19 .