Here 4 positions of a cube are shown. Which sign will be opposite to '+'?

The colours adjacent to yellow are orange, blue, red and rose. Hence violet will be opposite to yellow.

In first two positions of dice one common face containing 5 is same. Therefore according to rule no. (3) the face opposite to the face which contains 2 point, will contains 6 points.

In these 2 positions one common face with number 3, is in same position. Hence according to rule (3), 1 is opposite to 6 and 4 is opposite to 2. Therefore 5 is opposite to 3.

Here the common faces with 4 dots are in same positions.

Hence 2 will be opposite to 5.

The letters of the adjacent faces to the face with letter A, are B, F, C and E. Hence D is the letter of the face opposite to the face with letters (A).

In these 2 positions of a dice, one common face having points 3 is in the same position. Hence according to rule (3), there will be 4 points on the required face.

According to the rule no. (3), common faces with number 3, are in same positions. Hence the number of the opposite face to face with number 5 will be 6.

According to the rule no. (3), common faces with number 2 are in same positions. Hence when the digit 5 is on the bottom then 1 will on the upper surface.

As the numbers 2, 3, 4 and 5 are adjacent to 6. Hence the number on the face opposite to 6 is 1.

The adjacent faces to the face which 3 points have 2, 1, 4 and 6 points. Hence on the face which is opposite to the face which contains 3 points, there will be 5 points.