ANSWER:
2.5 days.
STEP-BY-STEP EXPLANATION:
We have the following equation:
[tex]\frac{1}{4}+\frac{1}{7}=\frac{1}{t}[/tex]
We solve for t:
[tex]\begin{gathered} \frac{1\cdot7+4\cdot1}{4\cdot7}=\frac{1}{t} \\ \frac{11}{28}=\frac{1}{t} \\ t=\frac{28}{11}\approx2.5\text{ days} \end{gathered}[/tex]
Therefore, if they work together, they could paint the house in about 2.5 days.
