Question

Emily is four years old. her big sister amy is three times as old as emily. how old will amy be when she is twice as old as emily?

Answer 1

Let's use E to represent Emily
And use A to represent Amy.

So, E = 4
      A = 12             come from (4 x 3)

These numbers are a factor of 4, so the easy way is to try to add each age wit 4, so 4 years later :

E = 4 + 4 = 8 years Old
A = 12 + 4 = 16 years old . . . .(Amy is 2 times older than Emily) 

So the answer is 8 years old