1 XL: it represents “extra large”, a Microsoft spreadsheet package (Excel), and 40 in Roman numerals, respectively.
2 The arithmetic is being performed on the number of letters in each word: two (3) + ten (3) = twenty (6); two (3) x ten (3) = seventeen (9); seventeen (9) - two (3) = eleven (6); seventeen (9) / two (3) = two (3); two (3) + two (3) = eleven (6).