Correct

相反数

/ xiāngfǎn shǔ / 
Strokes

Example

As a Noun

opposite number(s) ［numbers with the same absolute value but with opposite signs, positive or negative］

1
  
-
5
5
hé
和
  
+
5
5
hù
互
wéi
为
xiāngfǎn
相反
shǔ
数
  
。

-5 is the opposite number of +5 and vice versa.