Question

The gestation period of humans (266 ​days) is___ percent longer than the gestation period of pigs(115 days).

Answer 1

If we take 115 to be the 100%, how much is 266 off of it then?

$\bf \begin{array}{ccll} amount&\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 115&100\\ 266&p \end{array}\implies \cfrac{115}{266}=\cfrac{100}{p}\implies p=\cfrac{266\cdot 100}{115} \\\\\\ p\approx 231.3$

so 266 is about 231% of 115, which is 131% more than 115.