Answer: Option D. -> Rs. 288
$$\eqalign{
& {\text{Market price of the article }} \cr
& {\text{ = }}210 \times \frac{{120}}{{100}} \times \frac{{100}}{{87.5}} \cr
& = {\text{Rs}}{\text{. 288}} \cr} $$

Answer: Option D. -> Rs. 80
$$\eqalign{
& {\text{Given}}\,{\text{A}} = 2400 \cr
& {\text{R}} = 5\% \cr
& {\text{T}} = 4{\text{year}} \cr
& \therefore \,TD\, = \frac{{A \times R \times T}}{{100 + R \times T}} \cr
& TD = \frac{{2400 \times 4 \times 5}}{{100 + 20}} \cr
& TD = {\text{Rs}}{\text{. }}400 \cr
& \therefore \,{\text{S}}{\text{.I}}{\text{.}} - {\text{TD}} = \frac{{TD \times R \times T}}{{100}} \cr
& = \frac{{400 \times 5 \times 4}}{{100}} \cr
& = {\text{Rs}}{\text{. 80}}{\text{}} \cr} $$

Answer: Option D. -> Rs. 37.40
$$\eqalign{
& {\text{Cost of ratio}} \cr
& = \frac{{286}}{{130}} \times 100 \cr
& = {\text{Rs}}{\text{. 220}} \cr
& {\text{Selling price of ratio}} \cr
& = 286 \times \frac{{90}}{{100}} \cr
& = {\text{Rs 257}}{\text{.40}} \cr
& {\text{Profit}} = 257.40 - 220 \cr
& = {\text{Rs 37}}{\text{.40}} \cr} $$