You can complete one-tenth of a task in an hour. Your friend can complete two-fifths if the same task in an hour. How long will it take to complete the task if you work together?

When a whole number is multiplied by 104, how does the placement of the decimal point change? a. it moves ten places to the right. b. it moves four places to the left. c. it moves ten places to the left. d. it moves four places to the right.