Group task sums the numbers up, wrongly

[Kay]

Hi all,

I am confused.
I entered a task with some subtasks
I used Fixed work for all tasks.

Name effort duration resource
summary task 90d 65d
task 1 0d 0d Michael 40%
task 2 1d 2.5d Michael 40%
task 3 19d 47.5d Michael 40%
task 4 2d 5d Michael 40%
task 5 1d 2.5d Michael 40%
task 6 2d 5d Michael 40%
task 7 0d 5d
task 8 0d 0d

why does this add up to 90 days of work and 65d of duration where it
should be 25 and 67.5

Thanks

Kay