Algebra age question

Question

four years ago the father's age was three times the age of his son the total of the ages of the father and son after 4 years will be 64 years what is the father's age at present

Answer 1

F = father, S = son

F-4 = 3(S-4) F-3S= -8

F+4+S+4 = 64 F+S = 56

Solving those 2 equations yields F = 40 ad S = 16