Math algebra help please

Question

Slove each system of three liner equations containing the unknown by using the elimination method

x-3y+z=5

3x+y-4z=13

-4x-4y+2z=0

Answer 1

x=11/13

y=-32/13

z=-42/13

plug them in to each of the 3 equations, they work.

take the 3rd equation, divide by 2 to get -2x -2y +z = 0

subtract it from the 1st equation to get 3x - y = 5

take the 2nd and 3rd equations to get 5x+7y =-13

multiply 3x-y=5 by 7, then add the result to 5x_7=-13 to get 26x =22 and x = 11/13

3(11/13) -y = 5

y = 33/13 -65/13 = -32/13

now plug x= 11/13 and y=-32/13 into any of the 3 equations and solve for z =-42/13