$a)420-30=420-20-10=400-10=390$

$282-95=282-82-10-3=200-10-3=190-3=187$

$b)1,34-0,2=1,14$

$2,8-1,9=2,8-1,8-0,1=1-0,1=0,9$

 

$c)5-\frac{1}{7}=4\frac{6}{7}$

$2\frac{1}{3}-\frac{2}{3}=1\frac{4}{3}-\frac{2}{3}=1\frac{2}{3}$

 

$d)2\frac{3}{5}-1\frac{1}{5}=1\frac{2}{5}$

$2\frac{1}{5}-1\frac{3}{5}=1\frac{6}{5}-1\frac{3}{5}=\frac{3}{5}$