Statement $$\text{A}$$ is correct.  In the amount of pocket money that each has be $$x$$.  In $$2007$$, John has $$1.1\times0.9x=0.99x$$ while Mary has $$0.9\times1.1x=0.99x$$. 
In $$2005$$, both John and Mary have the same amount of pocket money per month. In $$2006$$, John had an increase of $$10\textbackslash\%$$ and Mary a decrease of $$10\textbackslash\%$$ in their monthly pocket money. In $$2007$$, John had a decrease of $$10\textbackslash\%$$ and Mary an increase of $$10\textbackslash\%$$ in their monthly pocket money.  $\textasciitilde$  John had a~\uline{~~~~~~~~~~}~$\textbackslash\%$ increase/decrease in his pocket money in $2007$ compared to $2005$.  Mary had a~\uline{~~~~~~~~~~}~$\textbackslash\%$ increase/decrease in her pocket money in $2007$ compared to $2005$.  $\textasciitilde$  Which one of the following statements is correct? 
Options:
[a] Both have the same amount of pocket money now. 
[b] John has more pocket money now. 
[c] Mary has more pocket money now. 
[d] It is impossible to tell who has more pocket money now. 