Ten minus four equals six.
He probably says that stuff just to get attentions from girls.
I pulled the trigger and shot the frying pan.
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means pull and the verb version vocab means to pull.
This word has another meaning! When you pull numbers away from other numbers, what you're really doing is subtracting them. That's why this word also means to subtract.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. The reading (ひ) is the same as the one you learned for the kanji, meaning you should already know it!