Assuming you are asking how much weed you get for 20 dollars, it depends on many factors. Generally, low quality pot goes 3.5 grams for 20 dollars, and high quality goes 1 gram for 20 dollars. But it all depends on what kind of a business man your dealer is.
The product of 20 and 20 is 400
20
half of 20 is 10
roughly £25($20)
20 pounds
20 - 50 = -30
20% = 0.20
16.
20
20 dollars
20 quadrillion.
20 cents