Tính tổng :
a) 25 + (–17) –15
b) (–20) + (–7)
c) S1 = 1+ (–2) + 3 + (–4) +…+ 2001 + (–2002)
d) S2 = 1+ (–3) + 3 + (–7) +…+ 1999 + (–2002)
e) S3 = 1+ (–2) + (–3)+ 4+5+(–6)+( –7)+8+…+1997+(–1998)+( –1999)+2000
f) (325 – 47)+(175 – 53)
g) (756 – 217) – (183 – 44)
h) (–2104) – 2015 + 2016
mai nộp rồi