To Solve
To Solve Something, To Untie Something
transitive verb, godan verb
とく
得 (とく) Benefit, Profit, Advantage, Gain
解く (とく) To Solve, To Solve Something, To Untie Something
解ける (とける) To Be Solved, To Come Undone, To Be Cleared
解ける is intransitive because you don't have a care ける in the world.