Let's solve the equation step by step.
First, we have the equation:
$$13\frac{17}{35} - x = 20 - 13\frac{27}{28}$$
To isolate $$x$$, we can rewrite the equation as:
$$x = 13\frac{17}{35} - (20 - 13\frac{27}{28})$$
$$x = 13\frac{17}{35} - 20 + 13\frac{27}{28}$$
Now, let's rewrite the mixed numbers as improper fractions:
$$13\frac{17}{35} = \frac{13 \cdot 35 + 17}{35} = \frac{455 + 17}{35} = \frac{472}{35}$$
$$13\frac{27}{28} = \frac{13 \cdot 28 + 27}{28} = \frac{364 + 27}{28} = \frac{391}{28}$$
Substitute these improper fractions back into the equation:
$$x = \frac{472}{35} - 20 + \frac{391}{28}$$
To combine these terms, we need a common denominator for the fractions. The least common multiple (LCM) of 35 and 28 is 140.
So, we convert the fractions to have a denominator of 140:
$$\frac{472}{35} = \frac{472 \cdot 4}{35 \cdot 4} = \frac{1888}{140}$$
$$\frac{391}{28} = \frac{391 \cdot 5}{28 \cdot 5} = \frac{1955}{140}$$
And rewrite 20 with the same denominator:
$$20 = \frac{20 \cdot 140}{140} = \frac{2800}{140}$$
Now we have:
$$x = \frac{1888}{140} - \frac{2800}{140} + \frac{1955}{140}$$
$$x = \frac{1888 - 2800 + 1955}{140}$$
$$x = \frac{-912 + 1955}{140}$$
$$x = \frac{1043}{140}$$
Now, convert the improper fraction back to a mixed number:
$$x = \frac{1043}{140} = 7\frac{63}{140}$$
We can simplify the fraction $$\frac{63}{140}$$ by dividing both numerator and denominator by 7:
$$\frac{63}{140} = \frac{63 \div 7}{140 \div 7} = \frac{9}{20}$$
So, the final answer is:
$$x = 7\frac{9}{20}$$
Answer: $$7\frac{9}{20}$$