CP of C = SP of B = 1040
CP of B = SP of A=
$\frac{SP*100}{100± r}$ =$\frac{1040*100}{100-20}=\frac{1040*100}{80} = 1300$
CP of A =$\frac{1300*100}{100+30}=\frac{1300*100}{130}=1000$
Profit of A= SP of A - CP of A
=1300 - 1000
=300
Hence,None of these Should be the Answer.