Reckless Restless Math puzzles

The world has been invaded by creatures from another realm! Take the role of a hoplite and solve creative mathematical puzzles to defeat them.
You'll lose hit points for each combat he performs. If your hit points fall below the knockout threshold you will be knocked and forced to restart the level. However, a Goddess will help you on your adventure! If your hit points drop to 0 or below the Goddess will revive and fully heal you!
Try to figure out the proper order of combats to avoid being knocked out and do not forget to force 0 or less hit points to be fully healed!!