Comment by losvedir

6 hours ago

> How did you actually make that deduction?

Think of it on a number line. Mary is 24 now, Ann was 12 then. There's a point somewhere between the two, representing Mary's age at that time.

     ---*-------*---------------*--------
        12      ?               24

The problem states that time has passed such that Mary has aged to 24 and Ann has aged to that point. You can think of time passing as a line growing out of each of them:

     ---*===----*===------------*--------
        12      ?               24

Since time progresses equally for both of them, and Ann is now that mystery age, and Mary is now 24, you can see that the distance from "12" to "?" has to be the same distance as "?" to "24".

2 comments

losvedir

seemaze 6 hours ago

That's pretty much how I approached it;

                   A1   M1
              A0   M0
    +----+----+----+----+----+
    0    6    12   18   24

SV_BubbleTime 2 hours ago

> Since time progresses equally for both of them,

Wild assumption. I saw absolutely nothing in the text to indicate their relative velocities.