Step-by-step explanation:
Based on the given conditions,
Formulate:(100-80)÷80
Calculate the sum or difference:20/80
Cross out the common factor:1/4
Multiply a number to both the numerator and the denominator:1/4×25/25
Write as a single fraction :25/4×25
Calculate the product or quotient :25/100
Rewrite a fraction with denominator equals 100 to a percentage:25%
Answer : 25%
