4y+z=56 3y + 6z = 63

3y + 6z = 63

3y+6z-6z=63-6z

3y=63-6z

3y/3=63-6z/3

y=21-2z

4y+z=56 sub in y and solve for z

4(21-2z)+z=56

84-8z+z=56

84-7z=56

84-84-7z=56-84

-7z=-28

-7z/-7=-28/-7

z=4

y=21-2z

y=21-2(4)

y=21-8

y=13