360 degrees in a circle
360 degrees minus 90 degrees (the right angle of the square) = 270 degrees
270 degrees divided by 2 = 135 degrees
f = 135 degrees
Answer:
150
Step-by-step explanation:
Let p be: John goes to the beach
Let q be: He will go surfing.
Then in symbolic form, the argument becomes:

p ⇒ q
p
---------------------
∴ q
An argument is valid if the conjuction of the premises implies the conclusion.
p | q | p ⇒ q | (p ⇒ q) ∧ p | [(p ⇒ q) ∧ p] ⇒ q
---------------------------------------------------------------------\
F | F | T | F | T
F | T | T | F | T
T | F | F | F | T
T | T | T | T | T
The table above shows that the argument is a tautology.
Hence, the argument is valid