Given: Vendor mixes 13 kg of millet at Rs.10 per kg with 15 kg of millet of other variety at Rs.18 per kg Formula Used: Profit = S.P - C.P EXPLANATION & CALCULATIONS : C.P. of 28 kg millet = Rs. ( 13 x 10 + 15 x 18 ) ⇒ Rs. ( 130 + 270 ) = Rs. 400. S.P. of 28 kg millet = Rs. (28 x 15) ⇒ Rs.420. Profit = S.P. of 28 kg millet - C.P. of 28 kg millet ⇒ 420 – 400 = 20 Profit percentage = (Profit /Cost Price) x 100 ⇒(