Children whose parents are dead are called orphans.
The relative pronoun "whose" is used to show possession or relationship. In this case, it shows that the parents belong to the children.
Ratio Notation
36:80 Represents a ratio of 36 to 80.
80:36 Represents a ratio of 80 to 36.
He is indifferent to his friends.
The correct preposition to use with "indifferent" is "to".
Indifferent to: This phrase expresses a lack of interest, concern, or feeling towards a particular thing or person.
DSLR stands for Digital Single-Lens Reflex.
DSLR cameras use a mirror mechanism to reflect light from the lens to an optical viewfinder.