Three babies A, B and C cry out at every interval of time. Baby A cries out at every 20 minutes, while B
cries out at every 30 minutes and C at every 40
minutes. If they are observed at the same time, after
what time will the three of them cry together?​

LCM of 20, 30, and 40

LCM = 120

they would cry together for the first time in 120 minutes.

the answer is below :)

Step-by-step explanation:

for this we have to use lcm of 20 30 and 40

2|20,30,40

2|10,15,20

2|5,15,10

5|1,3,2

2|1,3,1

3|,1,1

120÷60

after 2 hours

sorry not sure

step-by-step explanation:

for the friend request.

when a figure, such as triangle (xyz) is reflected over the line y = x to create x'y'z' the x-coordinates and y-coordinates of the original image (pre-image) will be reversed for the image. (e.g., (x, y) > (y, x)) this means that the pre-image position of the x- and y-coordinates switch places which in turn provides a mirror like image of the original xyz.  

i notice that when i draw a line segment from x to x', that the points are parallel from each other -- they are exactly across from each other and do not intersect with any other points.  

yes, think i would see the same characteristic if you drew the line segment connecting y with the reflecting line and then y' with the reflecting line because of the essence of reflections. because it is a mirror image, each point was effected the same way which leads me to conclude that they same would apply to y and y'.