Ravish sold his motorcycle to Vineet at a loss of 28%.

Solution:

Let the cost price of the motorcycle for Ravis $h$ be Rs. $\mathrm{x}$.

$\operatorname{Loss} \%=28 \%$

Therefore, $\mathrm{SP}=\mathrm{CP}\left(\frac{100-\text { Loss } \%}{100}\right)$

$\mathrm{SP}=$ Rs. $x\left(\frac{72}{100}\right)$

Selling price of the motorcycle for Ravish $=$ Cost price of the motorcycle for Vineet

Money spent on repair $s=$ Rs. 1680

Therefore, $t$ otal cost price of the motorcycle for Vineet $=$ Rs. $\left(x\left(\frac{72}{100}\right)+1680\right)$

Selling price of the motorcycle for Vineet $=$ Rs. 35910

Profit $\%=12.5 \%$

$\mathrm{SP}=\mathrm{CP}\left(\frac{\text { Profit } \%+100}{100}\right)$

$\Rightarrow 35910=\left(\frac{72 x}{100}+1680\right)\left(\frac{12.5+100}{100}\right)$

$\Rightarrow 35910 \times 100 \times 100=(72 x+168000)(112.5)$

$\Rightarrow 359100000=8100 x+18900000$

$\Rightarrow 340200000=8100 x$

$\Rightarrow x=$ Rs. 42000

Therefore, Ravis $h$ bought the motorcycle for Rs. 42000