a) \((–13 ) + (–15) + (–8)\)
\(= – (13 + 5 + 8)\)
\(= –36.\)
b) \(500 – (–200 ) – 210 – 100\)
\(= 500 + 200 – 210 – 100\)
\(= 500 + 200 – (210 + 100)\)
\(= 700 – 310 = 390.\)
c) \(–(–129) + (–119) – 301 + 12\)
\(= 129 – 119 – 301 + 12\)
\(= (129 + 12) – (119 + 301)\)
\(= 141 – 420\)
\(= –279.\)
d) \(777 – (–111) – (–222) + 20\)
\(= 777 + 111 + 222 + 20\)
\(= (777 + 111 + 222) + 20\)
\(= 1110 + 20 = 1130. \)