90, when A completes 1, the ratio of B's completed tasks to B's unfinished tasks is 1: 4.

A is half finished.

B finished one fifth.

When A finishes all the tasks, B has 65,438+0 tasks left.

Neither A nor B has had a rest during this time.

Half the task was completed during this time.

B has finished seven fifths.

The speed ratio of Party A and Party B is 15 14.

Therefore, A produces 90 parts per hour.