Running at a constant speed, Andy can run around a circular track once in 40 seconds. Bob, running in the opposite direction, slaps hands with Andy every time they run past each other. If they only slap hands every 15 seconds, how many seconds does it take Bob to run around the track once

step-by-step explanation:

given that there are two triangles j'k'l' and jkl>

the former is got by dilating the second one.

when drawn on a grid, (graph paper) coordinates of vertices of first triangle is

(6,12)j, (9,6)k and (12,9)l

side jk has length = distance between j and k

=

side j'k'=distance between j' and k'

=

ie j'k'l' has sides 1/3 of that of corresponding sides of jkl.

hence scale factor of 1/3 is used to get j'k'l'from jkl

i'm guessing it might be 40.