1) -3x-4y=10 ==> - 3x = 10+4y ===> 3x= -10-4y==> x=(-10-4y)/3
Now replace x by its value in 2)
2) -6x+y=-16 ==> - 6[( - 10- 4y)/3] + y = -16 ==> -2[(-10-4y] +y =- 16
+20+8y+y =- 16==> 9y = - 16 - 20 ==> 9y = -36 & y = - 4.
Now replace y by (- 4) in any of the 2 equations & you will find x = 2
