On a string of red and blue lights, the red lights blink everyb3 seconds, and the blue lights blink every 5 seconds. how many times will they blink at the same time in one minute?

When will they blink together?
what is the smallest number they both mutiply to
3*5=15
so every 15 seconds
so at 15, 30, 45, 60 seconds
so 4 times if you count the time exactly at 1 minute