[tex]\displaystyle\bf\\\Bigg(\frac{51}{2k} \Bigg)\cdot\Bigg(-\frac{7k}{17} \Bigg)=-\frac{51\cdot 7k}{2k\cdot17} =-\frac{17\cdot 3\cdot 7}{2\cdot 17} =-\frac{21}{2} =-10,5[/tex]