Consider the following premises. It is late or William is writing a letter. It is not late or Linda is happy. It is cloudy. If William writes a letter, then Barbara is climbing a mountain. If Linda were happy, then Barbara is climbing a mountain. If it is cloudy, then John is a scientist. If Susan were a mechanic, then Barbara is not climbing a mountain. Can we infer the following from them? If we can, name the inference rule being used: It is late or William is writing a letter.
That is one of the premises. Therefore, the answer is yes.