A Bachelor’s degree is 120 hours more or less.

By the end of summer of the third year you would have (42×3) 126 hours.

This is how many of the accelerated colleges manage the workload to finish “a four year degree in only three years”.

Be forewarned – keeping up a schedule like this is very demanding. If you mis-schedule a single class it could throw you off by a whole semester.

Regarding your question about summer school – full time is usually 6 credit hours per session. My university, for instance, offered two 6-week summer sessions, so a full-time student who was enrolled for both sessions would complete 12 credit hours. Check your university’s website for the summer session options they offer (12 weeks, 9 weeks, etc.).