由题意可得,$\left\{\begin{array}{l}{4A+5B<400}\\{6A+3B>450}\end{array}\right.$,
所以$\left\{\begin{array}{l}{-4A-5B>-400}\\{6A+3B>450}\end{array}\right.$,即$A-B \gt 25 \gt 0$,
故$A \gt B$.
故答案为:$ \gt $,
由题意可得,$\left\{\begin{array}{l}{4A+5B<400}\\{6A+3B>450}\end{array}\right.$,
所以$\left\{\begin{array}{l}{-4A-5B>-400}\\{6A+3B>450}\end{array}\right.$,即$A-B \gt 25 \gt 0$,
故$A \gt B$.
故答案为:$ \gt $,