Answer
a) $y=12000x+126000$
b) $342,000
Work Step by Step
a)
$(7,210000)$, $(12, 270000)$
$m=(270000-210000)/(12-7)$
$m=60000/5$
$m=12000$
$y=mx+b$
$210000=12000*7+b$
$210000=84000+b$
$126000=b$
$y=12000x+126000$
b)
$2016-1998=18$
$y=12000x+126000$
$y=12000*18+126000$
$y=216000+126000$
$342000$