His salary in 2014 was 20,000 Tk. per month.
His salary in 2015 was = Tk. per month
100
His total income in 2015 was = Tk.
Again, his salary in 2016 was = Tk. per month
His total income in 2016 was = Tk.
And, his salary in 2017 was = Tk. per month
His total income in 2017 was = Tk.
His total income from 2015 to 2017 was = Tk.