How do you make 3 different parallelograms with area 18?

Answer 1

Select any number B. Draw two parallel lines that are B units apart.

Calculate 18/B and mark out segments of length 18/B on the two lines. They can be anywhere along the entire [infinite] lengths of the lines, though obviously, it is easier to work with them if there are reasonably near each other.

Join together the left ends of the two segments; join together the right ends. These parallelograms will have areas of 18 units.

You can (1) select just one segment on one of the parallel lines and three on the other, or (2) select three pair of segments on the two parallel lines or (3) draw a fresh set of parallel lines for each parallelogram.