Coded $t=-5,-3,-1,1,3,5$: $\sum y=533,\sum t^2=70,\sum ty=317$; $a=88.83,b=4.529$; $\hat y=88.83+4.529t$; 2019($t=9$)$\approx129.6$, 2020($t=11$)$\approx138.6$. OR five-year moving averages listed below.

Main part: $n=6$ (even), so code time in steps of 2: $t=-5,-3,-1,1,3,5$ for 2012–2017.

$a=\frac{\sum y}{n}=\frac{533}{6}=88.83,\qquad b=\frac{\sum ty}{\sum t^2}=\frac{317}{70}=4.529.$

Trend line: $\hat y=88.83+4.529\,t$ (each unit of $t$ = half a year; origin mid-2014.5).

For 2019, $t=9$; for 2020, $t=11$:

$\hat y_{2019}=88.83+4.529(9)=88.83+40.76=129.59\ \text{thousand},$

$\hat y_{2020}=88.83+4.529(11)=88.83+49.81=138.65\ \text{thousand}.$

OR part — five-yearly moving averages of profit (lakh ₹):