For this case, the first thing we must do is define a variable.
 We have then:
 x: number of hours it takes the second painter to paint the house working alone.
 We have then that the equation that models the problem is: 

 From here, we clear the value of x.
 We have then: 
 
 
 
 
 
 Answer:
 It would take the second painter to paint the house by himself about 4.8 hours.