[tex]answer \\ k = - 4 \\ solution \\ 2x + y - 6 = 0 \\ (5 \: k) \: is \: a \: solution \: so \\ x = 5 \: and \: y = r \\now \\ 2x + y - 6 = 0 \\ or \: 2 \times 5 + r - 6 = 0 \\ or \: 10 + r - 6 = 0 \\ or \: 10 - 6 + r = 0 \\ or \: 4 + r = 0 \\ or \: r = 0 - 4 \\ r = - 4 \\ hope \: it \: helps[/tex]