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Answer: If they worked together, it would take 31.5 minutes
Step-by-step explanation:
There's a certain formula for equations like this:
[tex]\frac{1}{t1} +\frac{1}{t2}=\frac{1}{tb}[/tex]
t1= the time it took for the first person to complete the task.
t2= the time it took for the second person to complete the task.
tb= the time it took for both of them to complete the task.
We have the values for both t1 and t2, but not for tb.
t1= 45
t2= 105
tb= x
[tex]\frac{1}{45} +\frac{1}{105} = \frac{1}{x}[/tex]
Now it's simple algebra, and all we need to do is solve for x
The LCM for both fractions is 315, so now we multiply BOTH sides of the equation by 315.
[tex]\frac{315}{45} + \frac{315}{105} = \frac{315}{x}[/tex]
This will simplify nicely, so now we just need to get x on the other side.[tex]7 + 3 = \frac{315}{x} \\\\\ 10*x = \frac{315}{x} * x[/tex]
[tex]10x = 315 \\\\x = 31.5[/tex]