3/20 is the same as 15/100 or 15%
so 10×3/20 would be the same as 10×15% or 150%
Is that what you were asking?
Answer: 285.2 kg
Step-by-step explanation:
Given
The volume of helium in the balloon is 
The density of the helium is 
Mass of the helium gas is given by the product of density and volume

Thus, the mass of gas is 285.2 kg
I prefer to use fractions for some irrational numbers.
For example, 1/3 is equal to an infinite 0.3333333333333333...
15x = 3x + 120 (subtract both sides by 3x)
12x = 120 (divide both sides by 12)
x = 100
Any rhombus is a parallelogram, but not the other way around. If you were to make a Venn Diagram, the "rhombus" portion is entirely inside the set of "parallelograms".
The same can be said about rectangles as well. Any rectangle is a parallelogram, but not the other way around.
If we overlapped the region of rectangles and rhombuses, then we form the region for squares. A square is a combination of a rhombus and a rectangle.
Any square has all four sides the same length (property of a rhombus) and all angles equal to 90 (property of a rectangle). Since a square inherits properties of a rectangle and rhombus, it automatically makes any square a parallelogram.
Check out the venn diagram below.