Tìm x: (–12) – (13 – x) = –15 – (–17).

(–12) – (13 – x) = –15 – (–17)

(–12) – (13 – x) = –15 + 17

(–12) – (13 – x) = 2

–13 – x = 2 + 12

–13 – x = 14

x =14 – 13

x = 1.