Answer:

Brackets are punctuation marks used in pairs to set apart or interject text within other text.

Does 12 - 8 + 3 mean 4 + 3 which is 7, or 12 - 11 which is 1 ?
To avoid such confusion brackets are used.

(12 - 8) + 3 means 4 + 3, which is 7; 12 - (8 + 3) means 12 - 11 which is 1
The brackets show which numbers in a calculation are combined together.

For example, ((4 x 5) - 9) - (3 - 2) = (20 - 9) - 1 = 11 - 1 = 10

Brackets are used in algebra to group terms together.