Tom's dad is 3 times older than him. In 15 years the sum of Tom's and his dad's ages will be equal to 102. How old are Tom and his dad now?

Assume that Tom's age now is x and that his dad's is 3x. Therefore, in 15 years Tom will be x+15 years old and his dad will be 3x+15 years old. Since the sum of their ages will be equal to 102, we can formulate the following equation:(x+15)+(3x+15)=102 , now adding up all the alike terms, we get:4x+30=102 ,subtracting 30 from both sides of the equation and then dividing by 4 we find that Tom is now 18 years old ((102-30)/4) and his dad is 54 years old (18x3).