Question

The answer give in book is 32. pls expalin how this amswer came

Answer 1

see this equation can be written this way
i+=i means i=i+i
i-- is a decrement operator ,It means that i value which is 12 will be stored and used afterwards if i is given there
--i means it is a decrement operator but minus sign is given before so i value would be reduce instantly..So now i value would be 12-1 which is equal to 11

Answer 2

i-- 

i+ = i-- + --i

i+ = 12 + 10 -> 12 because i-- is use first and do subtraction , 10 because --i is subtract first then use. Now i value is changed to 10.

i+=22 -> 22+10 =32 because a+=b is a= a+b

hope it will help you understand, if not revert back