Answer:
13 shirts
Step-by-step explanation:
First you try to find the amount for one shirt by dividing $12.90 by 3 which equals $4.30. Then you try to find the amount of shirts for $55.90 by dividing 55.90 by 4.30 which results into the final answer 13.
the sine function is a many-to-one function and therefore has no inverse function.
However if the domain is restricted to -90° ≤ x ≤ 90°
Then the function is one-to-one for this domain
Thus, 
x is defined as the angle such that - π/2 ≤ x ≤ π/2
5π/6 is therefore outwith the domain
Set the whole expression = to 0 and solve for x.
3x^(5/3) - 4x^(7/3) = 0. Factor out x^(5/3): x^(5/3) [3 - 4x^(2/3)] = 0
Then either x^(5/3) = 0, or 3 - 4x^(2/3) = 0.
In the latter case, 4x^(2/3) = 3.
To solve this: mult. both sides by x^(-2/3). Then we have
4x^(2/3)x^(-2/3) = 3x^(-2/3), or 4 = 3x^(-2/3). It'd be easier to work with this if we rewrote it as
4 3
--- = --------------------
1 x^(+2/3)
Then
4
--- = x^(-2/3). Then, x^(2/3) = (3/4), and x = (3/4)^(3/2). According to my 3 calculator, that comes out to x = 0.65 (approx.)
Check this result! subst. 0.65 for x in the given equation. Is the equation then true?
My method here was a bit roundabout, and longer than it should have been. Can you think of a more elegant (and shorter) solution?
13/ 52 = 1/4 chances.
There are 13 spades and 52 cards. You divide the spades and cards in the deck to find your chances of drawing one.
You have a 25% chance of getting a spade.
Now you put it back. Since you put it back, you still have the same number of cards and the same number of spades. So when you divide 13/52 again, the numbers are still the same. 1/4. 25% chance.
So, you still have a 25% chance the second time around.
