Answer:
m = 0
Step-by-step explanation:

Answer:
Option C, 14/21=9/21 is the proportion.
Step-by-step explanation:
Given:
a.5/7 = 10/12
b.9/15 = 12/18
c.4/6 = 8/12
d.14/21 = 9/12
We have to find the proportions.
In proportion two ratios are equal, as it has an equality sign in between so both side must be of same ratio in its simplest form.
Let's work with option C
⇒ 
To find the simplest form we have to divide the numerator and denominator with same digit (or its factor).
Simplest form of
=
,
= 
Simplest form of
= 
Both sides in option C have equal ratios of 2/3.
So 4/6=8/12 is in proportion.
Check the picture.
let the length of a side of each of the squares removed be x.
The box formed will have dimensions: 80-2x, 50-2x, x(the height)
So the volume can be expressed as a function of x as follows:
f(x)=(80-2x)(50-2x)x=
![[4000-160x-100x+4 x^{2} ]x=(4 x^{2}-260x+4000)x](https://tex.z-dn.net/?f=%5B4000-160x-100x%2B4%20x%5E%7B2%7D%20%5Dx%3D%284%20x%5E%7B2%7D-260x%2B4000%29x)
so

the solutions of f'(x)=0 gives the inflection points, so the candidates for maxima points,

solving the quadratic equation, either by a calculator, graphing software, or by other algebraic methods as the discriminant formula, we find the solutions
x=10 and x=33.333
plug in f(x) these values to see which greater:

cm cubed

which is negative because (50-66.666)<0
Answer: 18000 cm cubed