2,000 Tk.
Let, the cost price he Tk. x
Profit = Selling price – Cost price.
& Loss = Cost price – Selling price.
Now, According to question
1,920 —x = x — 1,280
x + x = 1,280 + 1,920
2x = 3,200
=> $x=\frac{3200}{2}$
=> x=1,600
The cost price of the article is Tk. l,600.
Now at 25% profit, the selling price will be = (1600+1600$\times \frac{25}{100}$) TK.
= = (1,600 + 400) Tk. = 2,000 Tk.
At 13.5% interest
Interest of 100 Tk. for 1 year = 13.5 Tk.
so, Interest of 100 for 5 years = (13.5 x 5) = 67.5 Tk.
so, Principal -interest = (100 + 67.5) = 167.5 Tk.
If principal interest Tk. 167.5 then principal amount = 100 Tk.
So, If principal interest ‘Tk. 1 then principal amount = $\frac{100}{167.5}$ Tk.
so, If principal interest 33,500 then principal amount = $\frac{100\times 33500}{167.5}$ = 20,000Tk.
Now principal, p = 20.000 TK
Interest. 1 = 40,600 – 20,000 = 20,600 Tk.
Interest rate, r= 13.5% = $\frac{13.5}{100}$
=> I = 7.6296
I=7.63
