Final answer:
When combining the work rate of two individuals who can complete 3/10 and 1/5 of a task in an hour respectively, they can finish half of the task in an hour together. Thus, it will take them 2 hours to complete the entire task when working jointly.
Step-by-step explanation:
The question involves calculating the combined work rate of two people working on a task together and then determining how long it will take them to complete the task as a team. If you can complete 3/10 of a task in an hour, and your friend can complete 1/5 of the task in the same hour, we need to add these fractions to find the combined work rate. Since 1/5 is equivalent to 2/10, combined, you can complete 3/10 + 2/10 = 5/10 or half of the task in one hour when working together.
Therefore, if working non-stop at this combined rate, it will take 2 hours to complete the whole task, because in each hour, half of the task is done. To calculate this, you divide 1 (representing the whole task) by 1/2 (representing the fraction of the task completed in one hour), which is the same as multiplying by the reciprocal, leading to 1 * 2/1 = 2 hours.