Answer: [tex]2\ hours\ and\ 55\ minutes[/tex]
Step-by-step explanation:
WE can use the following formula:
[tex]\frac{T}{A}+\frac{T}{B}=1[/tex]
Where "T" is the time time working together, "A" the time for person A working alon and "B" is the time for person B working alone.
Based on the data given in the exercise, we can identify that:
[tex]A=7\\B=5[/tex]
Therefore, substituting these values into the formula and solving for "T", we get that this is:
[tex]\frac{T}{7}+\frac{T}{5}=1\\\\\frac{12T}{35}=1\\\\T=(1)(\frac{35}{12})\\\\T=2.9167\ hours[/tex]
Since 1 hour has 60 minutes:
[tex](0.9167h)(\frac{60min}{1h})=55min[/tex]
Therefore, if they work together, it will take them 2 hours and 55 minutes to remove the shingles.