These are the exact skills you dropped points on — pulled from your actual test. Each mission is one Khan Academy skill. Re-teach = new ground, learn it fresh. Sharpen = you've got it, just shaky — tighten it up.
The target is 20 minutes a day in something a little harder than easy. Then answer one quick question — that's the part that actually builds the skills the test wants.
On the test, the essay was worth 10 points — the biggest single thing, and it's where the most ground is. Two tools here: write real essays with a structure, and drill the small mistakes.
These are the exact mistake-types you lost points on. Spot the fix. Getting good at catching them is the same skill as not making them.