Linear Algebra requires a different way of thinking. One of my kids, who breezed through everything through Calc BC in high school, took Linear her first semester in college and was instantly flummoxed. She hit the same “pass/fail or drop?” decision point; she was already in college, so it wasn’t an admissions-implications issue, but she sure didn’t want to tank her college GPA right out of the gate. She ended up going P/F and is convinced to this day that the prof gave her a “pity pass,” because she remained baffled by the material, and the tutor she belatedly started working with couldn’t help. By this time, she’d decided against the potential CS major that the class would’ve been required for, so she took her Pity P gratefully and moved on. But a student who intends to pursue a computational major (as taking Discrete implies) is going to need to grasp this material.
I’ve known other kids who found Linear easier than Calc. It all depends how one’s mind works!
I know others have said that a W looks worse and the student should stick it out, but I would still consider pulling the plug and starting fresh with this class in the future. (She could even retake it in the spring, and use the time between now and then to prepare, knowing what she knows now about the content.) As others have said, it depends on the nature and severity of her struggle here. Does she really fundamentally not “get it,” as was the case with my D? Or does she understand the main thrust of the class, but just isn’t getting an A?