Answer:
Dad=35, Son=15
Explanation:
Well since the dad is 20 year older then the son we can call the son x and the dad x+20. Now five years ago the father was 3 times older then the so we construct the following equation:
x+20−5=3(x−5)
x+15=3x-15
x=15
So now we know that the sons age is 15 meanimg that since the dads 20 years older then him, his age is 20+15 which is 35!