20 POINTS!!!!!
Shawna can paint a fence in 8 hours. Kevin can paint the same fence in 4 hours. How long will it take them working together? Which of the following equations could be used to solve this problem?

[tex]\Large{8t + 4t = 1}[/tex]

[tex]\Large{ ( \frac {1}{8} ) \cdot t + (\frac {1}{4} ) \cdot t = 1}[/tex]

[tex]\Large{( \frac {1}{t} ) \cdot 8 + (\frac {1}{t} ) \cdot 4 = 1}[/tex]

[tex]\Large{( \frac {1}{8} ) + (\frac {1}{4} ) = t}[/tex]