Thực hiện phép tính:

a) 483 + (−56) + 263 + (−64)

b) 371 + (−531) + (−271) + 731

c) 3251 − 243 − 3250

d) 279 − (145 + 279)

a) 483 + (−56) + 263 + (−64)

= 427 + 263 + (−64)

= 690 + (−64) = 262

b) 371 + (−531) + (−271) + 731

= (371 − 271) + (731 − 531)

= 100 + 200 = 300

c) 3251 − 243 − 3250

= 3251 − 3250 − 243

= 1 – 243 = −242

d) 279 − (145 + 279)

= 279 – 421 = −142.