Answer:
The total percent decrease is [tex]$a+b-\frac{a b}{100}$[/tex]
Step-by-step explanation:
Step 1: Finding the two percentage decrease
Step 2: Finding their difference
Step 1 of 2
Let the decrease by a% be 100-a
Then b% decrease is
[tex]$\begin{aligned}\frac{b}{100} \times(100-a) &=\frac{100 b-a b}{100} \\\frac{100 b}{100}-\frac{a b}{100} &=b-\frac{a b}{100}\end{aligned}$[/tex]
Step 2 of 2
The percentage difference between the two percentages is,
[tex]$\begin{aligned}&(100-a)-\left(b-\frac{a b}{100}\right)=100-a-b+\frac{a b}{100} \\&100-a-b+\frac{a b}{100}=100-\left(a+b-\frac{a b}{100}\right)\end{aligned}$[/tex]
Since 100 is the total percent [tex]$a+b-\frac{a b}{100}$[/tex] is the percentage decrease.