1.

Triangle $KLM$is similar to triangle $KNJ$.  
$JKM$ and $NKL$are straight lines.

$K\overset{\textasciicircum{}}{L}M=K\overset{\textasciicircum{}}{N}J$ and$L\overset{\textasciicircum{}}{K}M=y^{\circ}$.

$KL=6cm$, $KM=10.5cm$ and $KN=10cm$.
The area of triangle $JKN$ is 75 cm².
Calculate $y.$

$y$= ................................