Click "Generate New Worksheet" for new random problems, then "Print to PDF" and choose "Save as PDF" in the print dialog.
Algebra is a way of solving math problems when we do not know one of the numbers yet.
If there is a bag filled with identical gifts, and we know how much the whole bag weighs and how much each gift weighs, we can write an equation and solve for the missing information.
A letter can stand for the unknown number. We call this solving for x.
For example, 3x means 3 multiplied by x.