Fastest & simple method for Age problem

what is the easiest and fastest method to solve the below problem Current ages of a mother and her son are in the ratio 11:5. when the son becomes as old as his mother is now, then the ratio of his father's age to mother's age will be 19:17 and when the son becomes as old as his father is now, then the sum of his father's age and his age will be 170. what is the father's current age? a. 60 b. 65 c. 55 d. 70 can we solve above problem w/o taking any variable x/y and doing much calculation