How to solve age word problems?

Question

Roy is now 4 years older than Erik and half of that amount older than Iris. If in 2 years, roy will be twice as old as Erik, then in 2 years what would be Roy's age multiplied by Iris's age?

Is there any general method or are they all so confusing?

Answer 1

Roy is now 4 years older than Erik

$$ R = E + 4 $$

and half of that amount older than Iris.

$$ R = I + 2 $$

If in 2 years, roy will be twice as old as Erik

$$ (R + 2) = 2(E + 2) $$

then in 2 years what would be Roy's age multiplied by Iris's age?

$$ (R + 2)(I+2) = \;\; ? $$

Then you just solve the equations. Hopefully you can see that this method will apply to any similar problem equally well.

Answer 2

Hint: Set $E$ the age of Erik, $I$ the age of Iris and $R$ the age of Roy today. You are given that $$R=4+E \tag{1}$$ and $$R=2+I \tag{2}$$ if I understood correctly this one (I am not sure what "that amount" is in your formulation) and $$(R+2)=2(E+2) \tag{3}$$ and you want to find $$(R+2)\times (I+2)$$ (if I understood that correctly too). Now you can solve the system of the three equations (1), (2), (3) (please check if they are formulated correctly) in three unknowns $E, I$ and $R$. That is the general method, with the difficulty being in the correct formulation of the given relations.