solve
To find the answer to a problem or question.
To solve a problem means to find the answer or fix what's wrong. When you solve a math equation, you figure out what number makes it work. When you solve a puzzle, you put the pieces together correctly. When you solve a mystery in a book, you discover who did it and why.
Solving takes different skills depending on the problem. Sometimes you need logic and careful thinking, like when you solve a riddle. Sometimes you need to try different approaches until something works, like solving a Rubik's Cube. Sometimes you need creativity, like solving the problem of how to build a treehouse with limited materials.
Solving can mean untangling something complicated until it makes sense. A detective solves a case by untangling clues. A scientist solves a research question by untangling data and observations.
Not every problem has a clear solution. You can solve “2 + 2 = ?” easily, but solving “How can I be a better friend?” takes ongoing effort and thought. Still, the process of working toward an answer counts as solving, even when the answer isn't simple or permanent.