Task scheduling problem

Hi! I need help with finding a solution for optimal scheduling of task and people. I think this can be achieved using Excel Solver but I'm not sure where to begin

We have 5 tasks and 3 people. Each person takes the same amount of time to finish a task, it all depends on the time allocated to each task.

Tasks 1 and 2 can take between 5 and 15 days.
Tasks 3 and 4 can take between 25 and 35 days.
Task 5 takes between 35 and 45 days.

Having 3 people means that 3 tasks can have people assigned to them at the same time.

The time constraint for the tasks is that the total time for each layer/timeline (not sure of the best word here) is 40 days.

So a solution would be:

Tasks 1 and 2 are scheduled for 10 days.
Tasks 3 and 4 are scheduled for 30 days.
Task 5 is scheduled for 40 days.

Person 1 would work on Task 1 and then on Task 3.
Person 2 would work on Task 2 and then on Task 4.
Person 3 would work on Task 5.
This last part is already solved with the help of this great forum . https://www.excelforum.com/excel-gen...em-solver.html