A sells to B a scooter at a profit of $30\%$, B sells it to C at a loss of $20\%$ what profit did A earn if C paid Rs.1040 for the scooter ?

$\text{C.P}\left(\text{C}\right)=\text{S.P}\left(\text{B}\right)=1040$

$\text{L}\%=\frac{\text{L}}{\text{CP}}\times 100$

$20=\frac{\text{CP}-\text{SP}}{\text{CP}}\times 100$

$\frac{20}{100}=1-\frac{1040}{\text{CP}}$

$\frac{1040}{\text{C.P}}=1-\frac{20}{100}=\frac{80}{100}$

$\text{C.P}=\frac{100\times 1040}{80}$

$\text{C.P}\left(\text{B}\right)=1300$ 

$\text{C.P}\left(\text{B}\right)=\text{S.P}\left(\text{A}\right)=1300$

$\text{P}\%=30$

$\text{C.P}\left(\text{A}\right)=\frac{\text{SP}\times 100}{100+\text{P}\%}=\frac{1300\times 100}{100+30}$

$\frac{1300\times 100}{130}=1000$

$\text{C.P}\left(\text{A}\right)=1000$

$\text{S.P}\left(\text{A}\right)=1300$

$\text{Profit}=300$