Step-by-step explanation:
1）
[tex]shaded \: parts = 20 \\ cans \: of \: paint \: needed = 20 \div 6 \\ = 3 \frac{1}{3} \\ = 4[/tex]
2）63cm^2（just counting）
3）
[tex]area \: of \: shaded \: parts = 3 \times 3 \\ = 9[/tex]
