$a)$  

$\frac{1}{100}\cdot {360}^{\circ }=\frac{1}{100}\cdot 360\cdot 3600{}^{\prime \prime }=360\cdot 36{}^{\prime \prime }=12960{}^{\prime \prime }=216{}^{\prime }$  

 

$b)$  

$4^{\circ }\cdot \frac{1}{100}=\frac{1}{100}\cdot 4\cdot 3600{}^{\prime \prime }=144{}^{\prime \prime }=2{}^{\prime }24{}^{\prime \prime }$  

 

$c)$  

$\frac{1}{100}\cdot {15}^{\circ }=\frac{1}{100}\cdot 15\cdot 3600{}^{\prime \prime }=15\cdot 36{}^{\prime \prime }=540{}^{\prime \prime }=9{}^{\prime }$  

 

$d)$  

$\frac{1}{100}\cdot {12}^{\circ }=\frac{1}{100}\cdot 12\cdot 3600{}^{\prime \prime }=12\cdot 36{}^{\prime \prime }=432{}^{\prime \prime }=7{}^{\prime }12{}^{\prime \prime }$  

 

$e)$  

$\frac{1}{100}\cdot {42}^{\circ }=\frac{1}{100}\cdot 42\cdot 3600{}^{\prime \prime }=36\cdot 42{}^{\prime \prime }=1512{}^{\prime \prime }=25{}^{\prime }12{}^{\prime \prime }$