Question 204731
Let's say Dorothy age is d, Ricardo's age is r:

{{{system( d=r+6, d*r = 2*(d-6)*(r-6)) }}}

Replace d with r+6:

(r+6)*r = 2*(r+6-6)*(r-6)

Give this problem to my universal simplifier:

*[invoke explain_simplification "(r+6)*r = 2*(r+6-6)*(r-6)" ]

We can dismiss r=0 answer because it is nonsensical, so we have, r=18. Since d=r+6, dorothy's age = 18+6 = 24.