Area of a parallelogram is the product of its base and height.
Let the base be "b" and height be "h". So we can write:
Area = bh = 42 cm²
After the change, base is one-third. So the new length of the base will be: b/3
After the change, height is twice as long. So the new height will be : 2h
Area after the change =

Using the value of bh from equation above we get:
Area after the change =

cm²
So the area of new parallelogram will be 28 cm²