Try another version of this question Solve the system of equations. If the system has an infinite number of solutions, express them in terms of the parameter z. Get help:
`{(7x,-,6y,+,20z,=,26),(3x,+,y,+,5z,=,4),(3x,-,3y,+,9z,=,12):}`
x =
y =
z =
`2-2z`
`-2+z`
`z`