Question

a+=++a-5*(a++-10) where a =12 pls solve this evaluation using increment decrement

Answer 1

a+=++a-5*(a++-10)
a+=13-5*(13-10)
a+=13-5*3
a+=13-15
a+=-2
a=a-2
a=12-2=10

I have not compiled the program and checked the output. But 10 will most probably be correct

Answer 2

The output varies. 

In Turbo C the output is 12.

In gcc 5.3.0 the output is  13.