Answer: 0.83 hours 
Explanation:
Hi, to answer this question we have to write a system of equations: 
Kay can solve equations at the rate of 26 per hour (x), and he already solved 3 equations. 
Kay=3+26 x 
Dan D can solve equations at the rate of 20 per hour (x), and he already solved 8 equations. 
Dan d = 8+20x 
If both equations are equal: (they have solved the same number of equations) 
3+26x = 8+20x 
Solving for x (hours) 
26x-20x =8-3 
6x= 5 
x =5/6 
x = 0.83 hours 
Feel free to ask for more if needed or if you did not understand something.