Question 1007365
Let the father's age be x
Let Betty's age be y

x = 4y
x - 5 = 7 (y-5)
4y - 5 = 7 (y-5)
4y - 5 = 7y - 35
-3y = -30
y = 10

x = 4y = 4(10) = 40

Final Answer: 
Father's age = 40 years old