Let's evaluate each equation to determine which one is NOT true:
-
5 + 14 = 20 - 1
- Left side: 5 + 14 = 19
- Right side: 20 - 1 = 19
- 19 = 19 (True)
-
9 + 5 = 7 + 7
- Left side: 9 + 5 = 14
- Right side: 7 + 7 = 14
- 14 = 14 (True)
-
15 = 4 + 11
- Right side: 4 + 11 = 15
- 15 = 15 (True)
-
15 - 9 = 9 - 4
- Left side: 15 - 9 = 6
- Right side: 9 - 4 = 5
- 6 ≠ 5 (False)
The equation that is NOT true is 15 - 9 = 9 - 4.