Answer:
No
Step-by-step explanation:
Let's check the first statement with an example. 2 and 3 are positive numbers and their sum (5) is also positive so his first statement is true.
To check the second statement let's look at the negative numbers -1 and -8 for example. Their sum (-9) is also negative so his second statement is true.
To check the third statement let's look at the numbers 9 and -5. One is positive and one is negative, but their sum (4) is positive, so his third statement is false. However if we look at the numbers 4 and -7, their sum is negative so the third statement is partially false.
