If we assume that Lisa is x years old, then Richard will be (x + 6)years In 5 years time Lisa = x +5 years Richard = x +11 years sum will be 2x + 16 years 4 years ago Lisa = x-4 years Richard = x + 2 Sum will be 2x - 2 Therefore; 2(2x-2) = 2x +16 4x -4 = 2x +16 2x = 20 x = 10 Thus, the present age of Lisa is 10 years and that of Richard is 16 years