Yes, you are right, if it approaches from the left, the limit is infinity and if it approaches from the right, the limit is negative infinity. The limit does not exist because it reaches infinity as x approaches pi/2 and the limits are the same when the value is approached from the opposite directions.
In order to make back the money they spent ($1,137.50) plus $1500, they want to make

$2,637.50 total.
They want to make this amount by selling 350 agendas, so divide the amount they want to make by 350 to find the amount per book:

I rounded the answer to the nearest hundredth because the hundredth is the smallest amount we have in USD (the penny.)
So they need to charge at least $7.54 to make back their money plus $1500.
Hope I helped, and let me know if you have any questions :)
Answer:
8.94 (Rounded would be 9)
Step-by-step explanation:
By using the Pythagorean Theorem formula,
A^2+B^2 = C^2
You have the hypotenuse (c) = 12
and you have a leg (a) = 8
and you're trying to find another leg (b) = x
In order to find this, you'll have to change up the formula in order to find (B) instead of (C)
B^2 = C^2 - A^2
(B) = (12)^2 - (8)^2
(B) = 144 - 64
(B) = 80
Square root of 80
B = 8.9