The answer is it's poorly written notation and people will interpret the form different ways.
20/2(5+5) could mean either of these formats:
[tex] \frac{20}{2(5+5)} \\
\frac{20}{2}(5+5)}[/tex]
[tex] \frac{20}{2(5+5)}[/tex]
[tex] \frac{20}{2(10)}[/tex]
[tex] \frac{20}{20}[/tex]
[tex] =1[/tex]
[tex]\frac{20}{2}(10)}[/tex]
[tex]10(10)[/tex]
[tex]100[/tex]
Both of these are correct, but the question is what did the author of the formula intend? The point of the problem is to write your equations clearly. Neither answer is right or wrong.
