Answer:
When 2 people work together the total time equals
Total Time = Time 1 * Time 2 / (Time 1 + Time 2)
Let's solve for Time 1 (which will be Tim's time.)
7 hours = Time 1 * 9 / (Time 1 + 9)
7 * Time 1 + 63 = Time 1 * 9
63 = 2 * Time 1
Time 1 = 30.5 Hours (Tim's Time)
Double Check
Total = 30.5 * 9 / (30.5 + 9)
Total = 274.5 / 39.5
Total = 7 Hours
Again, Tim's Time is 30.5 Hours
Step-by-step explanation: