Foreign Tax Credit and Deduction under subsection 20(12)

[formerpatriot]

I did my son's tax return using Ufile.
I am going over the final T1 tax return and I am trying to understand every line.
I am down to one last unsolved mystery.

His T3 shows the following:
Box 25 (Foreign non-business income): $162.14
Box 34 (Foreign non-business income tax paid): $18.77

Being a student, his income is modest. Consequently, Ufile uses a combination of "Deduction under subsection 20(12)" (reported on line 23200 of the T1 tax return) and "Foreign tax credit" (calculated on form T2209 and reported on line 40500 of the T1 tax return).

The deduction under subsection 20(12) is $7.14.
How did Ufile arrive at that number?
Was it simply the amount that leads to the best overall result in terms of minimizing taxes owed to the CRA?

On line 1 of the T2209, Ufile wrote $11.42.
How in the world did Ufile arrive at that number?

Thank you in advance for your help.