Answer :
[tex]A:\\66\%=\frac{66}{100}=0.66\\\\0.66\cdot550\ gallons=363\ gallons\leftarrow answer\\\\\\B:\\\frac{550}{B}=\frac{11}{15}\to11B=550\cdot15\ \ \ /:11\to B=750\ (gallons)\leftarrow answer\\\\\\C:\\53\%=\frac{53}{100}=0.53\\\\0.53\cdot750\ gallons=397.5\ gallons\leftarrow answer[/tex]
[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]