Mathematically, yes. Realistically, no. The difference in their ages is the parent's age when the child was born. Let's say that the youngest possible is 12. Then the ratio would be 10:9 when the parent is 120 and the child is 108. Not likely.
It's because any number multiplied by 0 equals 0. We could put any 2 numbers other than 2.7 and 2.8 yet still get both sides of the equation = - 5.9 but the 2 sides are obviously not equal.
To do the test correctly he can use any number except 0.
