$\text{b, 3.}$ `\sqrt{1/4}` $-$ $\text{2.}$ `\sqrt{1/9}` $\text{+}$ `\sqrt{0,09}`
$\equiv$ $\text{3.}$ `1/2` $\text{-2 .}$ `1/3` $\text{+}$ `3/10`
$\equiv$ `3/2` $-$ `2/3` $\text{+}$ `3/10`
$\equiv$ `9/6` $-$ `4/6` $\text{+}$ `3/10`
$\equiv$ `5/6` $\text{+}$ `3/10`
$\equiv$ `25/30` $\text{+}$ `9/30`
$\equiv$ `34/30`
$\equiv$ `17/15`