math
posted by Aisha on .
A blue light every 30seconds. A red light blinks every 40seconds. If both lights blink at exactly 1:00pm, at what time will they blink at the same time again?

The least common multiple of 30 and 40 is 120.
30, 60, 90, 120
30, 80, 120
1:00 + 120 seconds = ?