Answer:
a decrease of 80%
Explanation:
Mr. Lui had lunch, he began with 50$ and came out with 10$
With that we would use the Percentage change equation
PC= 1.00- (amount left/total amount)
(PC means percentage change)
PC= 1.00- (10/50)
we can reduce 10/50 to 1/5 by reducing by 5
PC= 1.00 -(⅕)
now we would change the fraction to a decimal by dividing
5÷1= .20
PC= 1.00 - .20
PC=.80
move the decimal place twice to the right
80%