3.26086957 hours
The question into an equation would look like this:
15.17+0.09x=15.92-0.14x
Now, to solve for x, the number of hours, would look like this:
Rearrange
15.17+0.09x=15.92-0.14x ---> 0.09x+15.17=-0.14x+15.92
Subtract 15.17 from both sides
0.09x+15.17-15.17=-0.14x+15.92-15.17
0.09x=-0.14x+0.75
Add 0.14x to both sides
0.09x + 0.14x =-0.14x+0.75 + 0.14x
0.23x = 0.75
Divide both sides by 0.23
0.23x /0.23 = 0.75 /0.23
x = 3.2608695652173913043478260869565
And there you have it!
Hope this helps!
Let me know if you need anything else :)