Verified answer

VALID OR NOT VALID ARGUMENTS

if angles are linear pair, then the sum of the angles is 180°

• Valid
• The conclusion is TRUE.

if a man is good at math, then he can build a house

• Not Valid
• The conclusion is NOT TRUE. NOT ALL man that is good at math can build a house. It is because you need to study engineering and architecture before you can do that, meanwhile, there is some man that is good at math but they are working as Professional Mathematician, Math professor, or studying accountancy.

if a creature is a mammal, then it can swim

• Not Valid
• The conclusion is NOT TRUE. NOT ALL mammals can swim. Most of the mammals are land animals, but still, there are some aquatic and aerial mammals living in our ecosystem.

if it rain, then there is thunder

• Not Valid
• The conclusion is NOT TRUE. Sometimes, even when it rains there's no thunder you can hear.

NOTE:

• I provide explanations to my answers to prove my answer is correct. Hope it helps!