The first displayed crash shortens the baseline critical path at the cheapest available rate.
Crash B
On the baseline critical path, B has the cheapest crash cost per day.
choose B on the baseline critical path
One day
Crash B by 1 day.
B crash cost
The added cost is 2.
added cost=2
Recompute
After crashing B, both paths have length 7.
TABD=TACD=7