You can annul either, or both, of your tests, if you choose. This shifts the weight of the test (or both) to the final exam.
To do this, fill out the annulment form (on the course site), check which of the tests you are annuling, sign, and drop in the dropbox in the CS&E Building (where you dropped your lab assignments during term) by at least an hour before the final exam, which takes place at 7pm on Wednesday 20 April.