Assuming the line $f(x,y)=1\mathrm{.}5x-1\mathrm{.}2y-18\mathrm{.}0=0$ intersects the $y-$axis at point $P$ and $10$

the $x-$axis at point $Q$ :

$($a$)$ Determine the slope$-$based zone of the line PQ$.($Consider the line to have a

specific direction, that is$,$ from $P$ to $Q)$

$($b$)$ Formulate separate line equations for the remaining seven zones.

Give mathematical solutions and working details $,$ do not use codes.