The function

is a parabola concave up, whose solutions are

from here, you can use the quadratic formula

to find that the solutions of the parabola are 
So, the parabola is positive if
(which wouldn't make sense in our case) or 
So, if Tanya caters 25 meals she breaks even, and starting with the 26th meal she will begin to profit.
Answer:
12.5
Step-by-step explanation:
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?
The <em>instantaneous</em> rate of change of <em>g</em> with respect to <em>x</em> at <em>x = π/3</em> is <em>1/2</em>.
<h3>How to determine the instantaneous rate of change of a given function</h3>
The <em>instantaneous</em> rate of change at a given value of
can be found by concept of derivative, which is described below:

Where
is the <em>difference</em> rate.
In this question we must find an expression for the <em>instantaneous</em> rate of change of
if
and evaluate the resulting expression for
. Then, we have the following procedure below:




Now we evaluate
for
:

The <em>instantaneous</em> rate of change of <em>g</em> with respect to <em>x</em> at <em>x = π/3</em> is <em>1/2</em>. 
To learn more on rates of change, we kindly invite to check this verified question: brainly.com/question/11606037