Answer: 223.77 minutes
Step-by-step explanation:
For this exercise you need to use the following formula:
[tex]\frac{t}{t_A}+\frac{t}{t_B}=1[/tex]
Where [tex]t_A[/tex] is the individual time for object A, [tex]t_B[/tex] is the individual time for object B and [tex]t[/tex] is the time for A and B working together.
In this case, analizing the information given in the exercise, you can identify that:
[tex]t_A=390\\\\t_B=525[/tex]
Knowing these values you can substitute them into the formula and then you must solve for "t" in order to calculate how long will it take working together.
You get that this is:
[tex]\frac{t}{390}+\frac{t}{525}=1\\\\\frac{61}{13650} t=1\\\\61t=(1)(13650)\\\\t=\frac{13650}{61}\\\\t=223.77\ minutes[/tex]
