Find the buying price of each of the following items when a sales tax of $$8.5 \%$$ is added on them.
(i) a towel of $$Rs. 50$$ (ii) Two bars of soap at $$Rs. 35$$ each.
$$\textbf{Step I: Apply the formula of the buying price to calculate Price of Soap and Towel}$$
$$\text{As we know that Buying price = Marked price + Sales tax}$$
$$\text{So, Buying price of towel}=Rs.50+\dfrac{8.5}{100}\times 50$$
$$\text{So, Buying price of towel}=Rs.50+4.25=Rs.54.25$$
$$\text{Also, Buying price of 2 bars of soap}=2\times\left ( Rs.35+\dfrac{8.5}{100}\times 35 \right )$$
$$\text{Also, Buying price of 2 bars of soap}=2\times Rs.37.975=Rs.75.95$$
$$\textbf{Hence, buying price of a towel is Rs. 54.25 and that of 2 soaps is Rs. 75.95}$$