$a)$
$f(-3) = |2.(-3)-1|+2 = |(-6)-1|+2 = |(-7)|+2 = 7 + 2 = 9$
$f(\frac{2}{5})=$ $|2.\frac{2}{5}-1|+2=$ $|\frac{4}{5}-1|+2=$ $|\frac{4}{5}-$ $\frac{5}{5}|+2=$ $|\frac{-1}{5}|+2=$ $\frac{1}{5}+2=$ $\frac{1}{5}+$ $\frac{2}{1}=$ $\frac{1}{5}+$ $\frac{10}{5}=$ $\frac{1+10}{5}=$ $\frac{11}{5}$
$b)$
$f(x)=6 ⇔ |2x-1|+2=6$
$⇒ |2x-1|=6-4$
$⇒|2x-1|=4$
$TH1: 2x-1=4$
$⇒2x=4+1$
$2x=5$
$x=$ $\frac{5}{2}$
$TH2: 2x-1=-4$
$⇒2x=(-4)+1$
$2x=-3$
$x=$ $\frac{-3}{2}$
