A good problem

On a walk, my daughter says she's discovered
a math problem in nature.
"There were four crows flying and two landed in a tree
and two kept flying. Four take away two equals two.
It's a good problem," she says. "My teacher will like it."
I wonder which were the take aways,
the two up in the tree where Wallace Stevens can see them
or the two that kept flying, now out of sight of poetry?
The caw, caw, caw is almost like the answer,
two, two, two.
On one side four is reduced by two.
On the other side two remain or two have gone.
My daughter and I, the two of us,
keep walking for now, with the take aways,
and those still flying and those still here.