Three bells ring at the interval of 20 minutes, 30 minutes and 40 minutes. when will they ring together if they ring together at 9: 45 am? plz answer the question

So, they'll ring together again in 120 minutes.

120 min = 2 h
9:45 + 2:00 = 11:45

He will need 2,898 pieces of paper

Period is the time it takes for one “cycle” to complete. in the parent sine function, period is 2*pi since sin(0) = 0, sin(pi/2) = 1, sin(pi) = 0, sin(3pi/2) = -1, and sin(2pi) = 0. at that point, the sequence repeats itself. i’m not sure if your graph is similar to the sine function since you didn’t provide a picture, but you can find the period by looking at a graph.