[tex]\begin{gathered} \text{Ara of triangle=}\frac{1}{2}\times3\times6 \\ \text{Area of triangle=9 }ft^2 \\ \text{There are two triangle,so} \\ \text{Area}=2\times9=18ft^2 \\ \text{Now full area is,} \\ \text{Area}=6\times12+18 \\ \text{Area}=90ft^2 \\ need\text{ of quarts is}\Rightarrow\frac{90}{50} \\ \Rightarrow1.8\text{ quarts} \end{gathered}[/tex]
