Math 175 Precalculus is a six-unit transfer-level class, transferrable to the UCs, CSUs, and many private universities.
Math 175 Precalculus with Corequisite Support is two classes/CRNs: the six-unit transfer-level Math 175 Precalculus class *and* a two-unit Math 075 Corequisite Support class, which is basic skills (the corequisite support class is graded pass/no pass).
These two classes are linked so students must add both CRNs (course registration numbers) to their schedule. The classes are scheduled sequentially (next to each other).