Answer:
16 + 4 - 1 < 20
Step-by-step explanation:
16 + 4 - 1 = 19
It cannot be the first equation because 16+4-1 does not equal 19-1. 19 ≠ 18
It cannot be the second or third equation because 19 ≠ 20.
This leaves the last equation where 19 is less than 20. 19 < 20
