46 Two light houses ash their lights every 30 seconds and 40 seconds respectively. Given that they last ashed together at 10:40 A.M., when will they next ash together? (Chapter 1)

Respuesta :

30,60,90,120
40,80,120

they will both " ash " in 120 seconds (thats 2 minutes)...so they will both ash at 
10:42 a.m.