$a)t:9=a\mid \cdot 9$

$t=9a$  

 

$b)\frac{8}{t}=rt\ne 0r\ne 0$     

 

$\frac{8}{t}=r\mid \cdot t$

$8=rt\mid :r$

$\frac{8}{r}=t$

$t=\frac{8}{r}$

 

 

$c)\frac{t}{m}=3m\ne 0$

$\frac{t}{m}=3\mid \cdot m$

$t=3m$

 

 

$d)t:d=yd\ne 0$

$t:d=y\mid \cdot d$

$t=dy$

 

 

$e)\frac{kl}{t}=4t\ne 0$

 

$\frac{kl}{t}=4\mid \cdot t$

$kl=4t\mid :4$

$\frac{kl}{4}=t$

$t=\frac{kl}{4}$

 

 

$f)\frac{t}{ab}=ca\ne 0b\ne 0$

$\frac{t}{ab}=c\mid \cdot ab$

$t=abc$