Question 568845
Let K and d be the ages of Mr. King and his daughter, respectively. Then,


K = 4d


Four years ago, Mr. King was K-4 years old and his daughter was d-4 years old. Also, we have


K-4 = 6(d-4)


So now we have a system of two equations. We can replace K with 4d to obtain


4d-4 = 6(d-4) = 6d-24


You should get d = 10. Since K = 4d, K = 40.