Blockpad makes it easy to solve systems of equations in line with your calculations.
Start by inserting a solver section in a document.
Type in the equations as regular formulas, using new names for the variables you want to solve for. The new names should appear at the bottom of the section.
When you type the equations, you can reference values from the document like normal.
When the solver section has enough information to solve for the new variables, the results will appear next to the names at the bottom. Click on these results to use them in formulas.