First equation is D - M = 6 (1) Since in 5 years the sum of their ages will be 58, the sum of their current ages now is 58 - 2*5 = 48. So, your second equation is D + M = 48. Now add equations (1) and (2). You will get 2D = 6 + 48 = 54 ====> D = 54/2 = 27. Hence, M = 48 - 27 = 21. Answer. D is 27 years old; M is 21 years old.