Answer:
x = 19.9
Explanation:
These kinds of problems have a specific formula.
Formula: outside (whole) = outside (whole)
We could substitute our variables into this.
For the first line, our outside segment is b and the whole thing is a + b
For the second line, our outside segment is x, and the whole thing is x.

The
= 19.8997487421
Rounding to the nearest tenth, your answer is 19.9