Find out the mystery sequence hidden in the diminoes, dominoes, decide which number should replace the question mark.

80

Step-by-step explanation:

Basically, the first domino represents the tens place of the number and the second domino represents the units place. For a, we see that there are 3 dots on the first domino and 4 dots on the second domino so the number is 30 + 4 = 34. The same goes for b. For c, there are 6 tens and 11 ones so the number is 60 + 11 = 71. For d, there are 7 tens and 10 ones so the number is 70 + 10 = 80.

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'.