Answer:
10 times
Step-by-step explanation:
The lights blink at the same time (if they ever do) every 12 seconds, the least common multiple of the individual times. Then in 120 seconds, they will blink together ...
120/12 = 10
times.
_____
You could count 11 (simultaneous) blinks, if you count the one at the start of a period of 120 seconds and also the one at the end of that period. If you start marking time between (simultaneous) blinks, you will count only 10.
