الخطا فين:.She comes to see me three times a week for help with her arithmetics

[ابو بيشو]

اليك منى كل احترام وتقدير شكرا

She comes to see me three times a week for help with her
arithmetic.

mathematics (WITH -s) but arithmetic (WITHOUT -s): 'Arithemtic isn't
difficult if it is taught properly.'