Tilly the dog barks every 9 seconds. Billy the dog barks every 12 seconds.
They both bark at the same time.

After how many seconds will they next bark at the same time?

36 seconds

Step-by-step explanation:

36 is the lowest common multiple of 9 and 12.

According to this question, you must find the L.C.M

So,

L.C.M. (Least.Common.Multiple)

●You divide by prime numbers

●You take common and uncommon ones

●You Multiply

9= 3×3

12=2×2×3

L.C.M= 3× 2×2×3

=36 seconds

ANSWER= 36 SECONDS