21.8 - (7 19/20 - 8 3/5)

First, let's convert the mixed numbers to improper fractions:

7 19/20 = (20 * 7 + 19) / 20 = 159/20

8 3/5 = (5 * 8 + 3) / 5 = 43/5

Now, substitute the improper fractions back into the equation:

21.8 - (159/20 - 43/5)

Next, find a common denominator for the fractions inside the parentheses, which is 20:

21.8 - ((159 5) / (20 5) - (43 4) / (5 4))

21.8 - (795/100 - 172/20)

21.8 - (795/100 - 860/100)

21.8 - (-65/100)

Now, subtract the fractions inside the parentheses:

21.8 + 65/100

Now, find a common denominator, which is 100:

21.8 + 65/100 = 2180/100 + 65/100

Add the fractions together:

2180/100 + 65/100 = (2180 + 65) / 100 = 2245 / 100

Finally, simplify the resulting fraction:

2245 / 100 = 22.45

Therefore, 21.8 - (7 19/20 - 8 3/5) = 22.45.