How to put a line break in an equation in MS Word 2007 or newer

When in doubt, right-click. The context menu for equations includes a "manual break" command.

I just had the same problem, but solved it differently because I could not figure out the "manual break". I might be on Word 2010. My solution was to insert a matrix, one cell for each line that I required. I needed 5 lines, but more can be inserted.

Raymond Anderson Johannesburg