Answer :
hmmm the increase, wel is just the difference 367 - 312, which is 55.
now, if we take 312 to be the 100%, what is 55 off of it in percentage?
[tex]\bf \begin{array}{ccll} amount&\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 312&100\\ 55&p \end{array}\implies \cfrac{312}{55}=\cfrac{100}{p}\implies p=\cfrac{55\cdot 100}{312}[/tex]
now, if we take 312 to be the 100%, what is 55 off of it in percentage?
[tex]\bf \begin{array}{ccll} amount&\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 312&100\\ 55&p \end{array}\implies \cfrac{312}{55}=\cfrac{100}{p}\implies p=\cfrac{55\cdot 100}{312}[/tex]