Question

The lighthouse flashes their lights after every 20 seconds and 30 seconds. If they

flashed together at 7p.m, when will they flash together again?​

Answer 1

Step-by-step explanation:

HEY MATE ..

The least common multiple of 20 and 30 is 60, so the lights will flash again 60 seconds after 8pm, or at 8:01 pm exactly

Actually, despite the other answers, there's actually no way to answer this question with any certainty. If the two lighthouses INITIALLY flash at the same time, yes, they will flash together again after 60 seconds; however, if they flash any time OTHER than 20, 30, 40, or 60 seconds apart, they will never flash together.

Answer 2

Answer:

Step-by-step explanation:

Find the smallest number that both

20 and 30 divide into evenly

+120+%2F+20+=+6+

+120+%2F+30+=+4+

but,

 

+60%2F20+=+3+

+60%2F30+=+2+

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In 60 seconds, or 8:01 PM, they both

flash together