a)   $50\%$   kwoty $160\text{zł}$   to

$50\%=\frac{50}{100}=\frac{1}{2}$  


$\frac{1}{2}$   z $160$   to:

  $\frac{1}{2}\cdot 160=80\text{[zł]}$  

    $50\%$   kwoty $400\text{zł}$   to

$50\%=\frac{50}{100}=\frac{1}{2}$   ; 

$\frac{1}{2}$   z $400$   to:

$\frac{1}{2}\cdot 400=200\text{[zł]}$  



b) $10\%$   kwoty $300\text{zł}$   to

$10\%=\frac{10}{100}=\frac{1}{10}$  ;

$\frac{1}{10}$   z $300$   to

$\frac{1}{10}\cdot 300=30\text{[zł]}$  

$10\%$   kwoty $170\text{zł}$   to

$10\%=\frac{10}{100}=\frac{1}{10}$   ;

$\frac{1}{10}$  z   $170$   to

$\frac{1}{10}\cdot 170=17\text{[zł]}$  


c) $1\%$   liczby $900$    to

$1\%=\frac{1}{100}$  ;

  $\frac{1}{100}$   z $900$   to

$\frac{1}{100}\cdot 900=9$  

    $1\%$   liczby $4000$    to

$1\%=\frac{1}{100}$  ; 

$\frac{1}{100}$   z $4000$   to

$\frac{1}{100}\cdot 4000=\cdot \left(40\right)$  

d) $20\%$   liczby $40$   to

$20\%=\frac{20}{100}=\frac{1}{5}$  ;

  $\frac{1}{5}$   z $40$   to

$\frac{1}{5}\cdot 40=8$  


    20% liczby 250 to

$20\%=\frac{20}{100}=\frac{1}{5}$  ;

  $\frac{1}{5}$   z $250$   to 

$\frac{1}{5}\cdot 250=50$  


e) $25\%$   kwoty $40\text{zł}$   to

$25\%=\frac{25}{100}=\frac{1}{4}$   ; 

$\frac{1}{4}$   z $40$   to

$\frac{1}{4}\cdot 40=10\left[\mathbf{z}\mathbf{ł}\right]$  

$25\%$   kwoty $120\text{zł}$   to

$25\%=\frac{25}{100}=\frac{1}{4}$   ; 

$\frac{1}{4}$   z $120$   to

  $\frac{1}{4}\cdot 120=30\left[\mathbf{z}\mathbf{ł}\right]$  

f) 75% liczby 800  to

$75\%=\frac{75}{100}=\frac{3}{4}$  ;

$\frac{3}{4}$   z $800$   to 

$\frac{3}{4}\cdot 800=600$  


    $75\%$   liczby $2400$    to

$75\%=\frac{75}{100}=\frac{3}{4}$  ;

  $\frac{3}{4}$   z $2400$   to

  $\frac{3}{4}\cdot 2400=1800$