Answer:
The 1st and the 3rd one
Explanation:
2.3+(-2.3) ➡ 2.3 -2.3 = 0 ,so this option is correct
-3.7+(-4.1) ➡ -3.7 - 4.1 = -7.8 so this option isn't correct
-2.6-(-12/4) ➡-2.6 + 3 = 0.4 this option is also correct
(5/2)+(-2.5) ➡ 5/2 -5/2 = 0 this would be undefined because we can't divide 0 by 2 or any other rational numbers
E.72-(-100) ➡72+100= 172 this option is incorrect because 172 is positive