This sum will be solved in two parts. In 1st part, we find the C.P. and in 2nd part, we find the required S.P.
Part I:
S.P .of the air cooler = Rs 6800
Loss = 15% i.e, for every Rs 100 he is losing Rs 15.
∴ If C.P. is Rs 100, then S.P. Rs 100- Rs 15 = Rs 85
∴ If S.P is Rs 85, then C.P. = Rs 100
If S.P. is Rs 1, then C.P. = Rs 10085
If S.P. is Rs 6800, then C.P = Rs 10085×6800=Rs 100×80=Rs 8000.
Part II:
C.P. = Rs 8000
Profit = 10%
∴ Profit = 10% of Rs 8000 =10100×8000=Rs 800
∴ S.P. = C.P. + Profit = Rs 8000 + Rs 800 = Rs 8800.
Hence, the air-cooler should be sold for Rs 8,800 in order to make a profit of 10%