Final answer:
To find the regular price of the washing machine, divide the sale price of $400 by 4 to find the value of one fifth, which is $100, and then multiply by 5 to find the full price, which totals $500.
Step-by-step explanation:
If you save 1/5 the cost of a new washing machine during a sale, and the sale price is $400, we need to determine the regular price of the washing machine. To do this, we consider that the $400 represents 4/5 (since you're saving 1/5), of the full price.
Steps to calculate the regular price:
Firstly, divide the sale price by 4 to find the amount saved per fifth. $400 ÷ 4 equals $100.
Since $100 is 1/5 of the regular price, multiply $100 by 5 to find the full price. $100 x 5 equals $500.
Therefore, the regular price of the washing machine is $500.