Tham Khảo:

-(515-80+91)-(2003+80-91)

=-515+80-91-2003-80+91

(-515)-2003+(80-80)+(91-91)

=2518

cách 1

   - (515 - 80 + 91) - (2003 + 80 - 91)

= - ( 435 + 91 ) - ( 2083 - 91 )

= - 526 - 1992

=  - 2518

 - (515 - 80 + 91) - (2003 + 80 - 91)

= -515 + 80 - 91 - 2003 - 80 + 91

= -515 +( 80 - 80) + (90 - 90) -2003

= -515 + 0 + 0 -2003

= -2518

 - (515 - 80 + 91) - (2003 + 80 - 91)

= -515 + 80 - 91 - 2003 - 80 + 91

= -515 +( 80 - 80) + (90 - 90) -2003

= -515 + 0 + 0 -2003

= -2518

-(515-80+91)-(2003+80-91)

= -515+80-91-2003-80+91

= -2518

=-515-80+91-2003+80-91

=(-515-2003)-(80+80)+(91-91)

=-2518-160+0

=-2318+0

=-2318

a, ( 2002 - 79 + 15 ) - ( -79 + 15 )

= 2002 -79 +15 +79 -15

= 2002

b, - ( 515 - 80 +91 ) - ( 2003 + 80 - 91 )

= -515 + 80 -91 -2003 - 80 +91 

= -2518

a)  \(\left(2002-79+15\right)-\left(-79+15\right)=2002-79+15+79-15=2002\)

b)  \(-\left(515-80+91\right)-\left(2003+80-91\right)=-515+80-91-2003-80+91=-2518\)

p/s: chúc bạn học tốt

(35+75)+(345-35-75)

=35+75-345-35-75

=(35-35)+345+975-75)

(2002-79+15)-(-79+15)

=2002-79+15+79-15

=2002+(79-79)+915-15)

=2002.

-(515-80+91)-(2003+80-91)

=-515+80-91-2003-80+91

(-515)-2003+(80-80)+(91-91)

=2518.