To evaluate: The simplified form of the expression 10.7-(-9.8).

The given expression is 10.7 - (-9.8).
Write the subtraction in terms of addition as,
a-b=a+(-b)
The given expression becomes,
10.7-(-9.8) = 10.7 +9.8
Now, the two values are of same signs and for the addition of any two numbers of same signs, add their absolute values and then attach their common signs.
Absolute values of the numbers are,
|10.7| = 10.7
|9.8| = 9.8
Now, add the absolute value.
10.7+9.8 = 20.5
As the numbers are positive, the answer is also positive
So, the difference of the given expression is 20.5.
Final statement:
Therefore, the simplified form of the expression 10.7 - (-9.8) is ${\displaystyle \frac{5}{6}}$.