Answer:
16
Step-by-step explanation:
decreasing 20 in the ratio 4 : 5 , indicates
new quantity : old quantity = 4 : 5
let the new quantity be x, then by proportion
[tex]\frac{x}{20}[/tex] = [tex]\frac{4}{5}[/tex] ( cross multiply )
5x = 20 × 4 = 80 ( divide both sides by 5 )
x = 16
Thus 20 decreased in the ratio 4 : 5 is 16