Firstly, we'll fix the postions where the 
women will be. We have 
forms to do that. So, we'll obtain a row like:
The n+1 spaces represented by the underline positions will receive the men of the row. Then,
Since there is no women sitting together, we must write that 
. It guarantees that there is at least one man between two consecutive women. We'll do some substitutions:
The equation (i) can be rewritten as:
We obtained a linear problem of non-negative integer solutions in (ii). The number of solutions to this type of problem are known: ![\dfrac{[(n)+(m-n+1)]!}{(n)!(m-n+1)!}=\dfrac{(m+1)!}{n!(m-n+1)!}](https://tex.z-dn.net/?f=%5Cdfrac%7B%5B%28n%29%2B%28m-n%2B1%29%5D%21%7D%7B%28n%29%21%28m-n%2B1%29%21%7D%3D%5Cdfrac%7B%28m%2B1%29%21%7D%7Bn%21%28m-n%2B1%29%21%7D)
[I can write the proof if you want]
Now, we just have to calculate the number of forms to permute the men that are dispposed in the row: 
Multiplying all results:
2200 + 0.06s > = 2900.....with s representing her total sales
0.06s > = 2900 - 2200
0.06s > = 700
s > = 700 / 0.06
s > = 11666.67 <== her sales has to be at least this
Thrice means three, so 3 times the difference of x and 4.
3(x - 4) < 9
multiply 3 by all in parentheses
(3*x) + (3*-4) < 9
3x - 12 < 9
add 12 to both sides
3x < 21
divide both sides by 3
x < 7
ANSWER: x < 7
Hope this helps! :)
Answer:
The answer is $18.19cents
Step-by-step explanation:
20 dollars minus 15 percent is 17 dollars plus 7 percent tax is 18.19
Hope this helps.
