1. **Rounding off the number 728.35** The problem asks to round the number 728.35. Usually, rounding is done to the nearest whole number or decimal place. Here, we will round to the nearest whole number. Rule: If the digit after the decimal point is 5 or more, round up the integer part by 1. Since the decimal part is .35, which is less than .5, we round down. **Answer:** 728 2. **Simplify the expression 5 + \frac{2}{3} of 6** "Of" means multiplication. So, the expression is: $$5 + \frac{2}{3} \times 6$$ Calculate \(\frac{2}{3} \times 6 = 4\) Now add: $$5 + 4 = 9$$ **Answer:** 9 3. **Find the marked price of an electric appliance bought at 20% discount** The problem is incomplete but usually, if a seller buys an appliance at a 20% discount, the marked price is the original price before discount. Let the marked price be $M$. The selling price after 20% discount is: $$\text{Selling Price} = M - 0.20M = 0.80M$$ If the cost price is known, and the seller wants to find the marked price, more information is needed. Since the problem is incomplete, we cannot solve this part. **Summary:** 1. Rounded number: 728 2. Simplified expression: 9 3. Marked price problem incomplete