[tex]V_A-capacity\ water\ tank\ A \\V_B-capacity\ water\ tank\ B\\\\ A.\\\\66\%\cdot550=0.66\cdot550=363\ [gallons]\\ \\B.\\\\ \frac{V_A}{V_B} = \frac{11}{15}\ \ \ \wdge\ \ \ V_A=550\ gallons \ \ \Rightarrow\ \ \ 11\cdot V_B=15\cdot 550\ /:11\\ \\ V_B=15\cdot50=750\ [gallons]\\ \\C.\\ \\ 53\% \cdot 750=397.5\ [gallons][/tex]