That is the image but smaller, so no one has to scroll a hundred times just to read the problem. Anyways, there are two methods to solve this problem.
To begin, we first find the "unit-rate". <------ a real link
For Trevon, that is 01/10 per hour. For Cody, that is 1/7 per hour.
Together, they paint 17/70 of the attic in one hour. The time they spent with the whole attic is just the reciprocal, which is 70/17. Sadly, this does not come out well, but you could just say 4 hours and 2/17 of an hour (Rounded to 4 hours and 7 minutes). Does not make sense, but that's the fault of the creator of the problem, as they should have known that this is not possible. (Or my fault for doing it wrong)
Using the formula:
ab/a + b = 7(10)/7 + 10 = 70/17, same as before, 4 hours and 2/17 of an hour. (Rounded to 4 hours and 7 minutes)