The comparison is between [the father's cell phone] and [the brother's cell phone]
爸爸的手机没有哥哥贵 would mean "my father's cell phone is not as expensive as my brother"
Either "爸爸的手机没有哥哥的手机贵" or "爸爸的手机没有哥哥的贵" would be correct
The comparison is between [the father's cell phone] and [the brother's cell phone]
爸爸的手机没有哥哥贵 would mean "my father's cell phone is not as expensive as my brother"
Either "爸爸的手机没有哥哥的手机贵" or "爸爸的手机没有哥哥的贵" would be correct
Ali