Excel can solve equations through several of its mathematical functions, but the single Excel tool that works on the largest variety of equations is the program's Solver Add-in.

Excel can solve for unknown variables, either for a single cell with Goal Seek or multiple cells with Solver.

The Solver add-in is included by default in Microsoft Excel. You only need to activate it to load it. Learn how to load Solver add-in in Excel if it is not showing.