Our expression is below
[tex]5(-3.4k-7)+(3k+21) = 0[/tex]
by solving it for the value of k
[tex](-17k-35)+(3k+21) = 0[/tex]
[tex]-17k+3k-35+21 = 0[/tex]
[tex]-14k-14 = 0[/tex]
[tex]-14k = 14[/tex]
[tex]k = \frac{14}{-14}[/tex]
[tex]k = -1[/tex]
