Answer:

Yes, y is a function of x.

Step-by-step explanation:
For a proportional relation, the equation is given by:

where k is the unit rate of change.
We were told that, Lin's sister earns $9.6 per hour.
This means k=9.6.
We substitute to get:

We could rewrite this as

Yes, y is a function of x.
To obtain an equation describing x as a function of y, we solve for x to get:

Answer:
X = 10
Step-by-step explanation:
The equation to use would be; 2x + 30 = 5x; because the baker is looking for enough to cover the costs, no more no less.
Then all you have to do is solve for the equation.
2x + 30 = 5x
Subtract 2x from each side
30 = 3x
Divide by 3
10 = x
The baker needs to sell 10 muffins in a day to make enough to cover the revenue.
Pi/4 radians
You're looking for the angle that has a secant of sqrt(2). And since the secant is simply the reciprocal of the cosine, let's take a look at that.
sqrt(2) = 1/x
x*sqrt(2) = 1
x = 1/sqrt(2)
Let's multiply both numerator and denominator by sqrt(2), so
x = sqrt(2)/2
And the value sqrt(2)/2 should be immediately obvious to you as a trig identity. Namely, that's the cosine of a 45 degree angle. Now for the issue of how to actually give you your answer. There's no need for decimals to express 45 degrees, so that caveat in the question doesn't make any sense unless you're measuring angles in radians. So let's convert 45 degrees to radians. A full circle has 360 degrees, or 2*pi radians. So:
45 * (2*pi)/360 = 90*pi/360 = pi/4
So your answer is pi/4 radians.
Both of the other angles should be 45. 180-90=90. 90 divided by 2 equals 45