Let x = the unknown number to get x = 6
Answer:

Step-by-step explanation:
Given : The formula 
We have to rearrange the given formula for 
Consider the given formula 
Multiply both side by 2, we have,

Divide both side by
, we have,

Simplify, we get,

Thus,
Answer:
If every line parallel to two lines intersects both regions in line segments of equal length, then the two regions have equal areas. In the case of your problem, every line parallel to the bases of the two parallelograms will intersect them in lines segments, each with a width of ℓ.