I admit a bit of difficulty in identifying with people who are very worried about their grades. I stopped worrying about my grades somewhere around fifth grade, when I missed a straight-A report card by one question on one spelling test and decided the stress wasn’t worth it for changing one B+ into an A-. But it’s a question instructors get, increasingly, as the final exam approaches, and students are almost never satisfied with the correct answers, especially when circumstances require a time machine. I suppose I understand the despair in that case.
Anyway, working out the minimum grade you need to pass — or what you need to get an A, or to get a B, or whatever you like — is an easy enough problem it’s surprising when students don’t work it out on their own. Maybe they don’t realize this is what they learn algebra for. But here’s how to do it.