Estimate the time, when a man's salary will be increased.

suppose 'n' as month pay his salary would be $18,100$ Taka.

So, $1000+10300+10600+10900....+18100$

now,

1st Figure of cluse, $a=10000$ .

Common difference , $d=300$

by the low,,,
$a+(n-1)d=18100$
or, $10000+(n-1)*300=1$
or, $n-1)*300=18100-10000$
or, $(n-1$ = $(n-1)*300=8100$
or, $n-1$ = $\frac{8100}{300}$
or, $n-1=27$
or, $n=27+1$
or, $n=28$
So 28 months later, Mr. Zahidul Alam monthly salary will be $18100$ Taka. Then in December 2016 after 28 months, ie in March, 2019. So in March, 2019 will be the correct answer.