Answer:
All below
Step-by-step explanation:
1. Before tax
500*0.7 (30% off means 100%-30% of the price = 70% or 0.7) = $350
2. Final selling price
350*1.13 (100%+13% as the price after adding 13% of tax to subtotal) = $395.5
First, find the equation
y = F(x) = x +3
Then plug in 2 for x ( you could also go to 2 on the x-axis to find the Y)
F(2) = (2)+3
F(2) = 5
The problem here is: Too many words.
If you boil the problem down to the bare facts, the question is:
"$210 is 15% of what number ?"
I'm pretty sure you can take it from there,
but here's the rest of it anyway:
$210 = 15% of (March amount)
$210 = 0.15 x (March amount)
Divide each side by 0.15 : $1400 = March amount .
Check:
1400 + 210 = 1610
1.15 x 1400 = 1610 yay!
Note: The equations written in this questions are not appropriately expressed, however, i will work with hypothetical equations that will enable you to solve any problems of this kind.
Answer:
For the system of equations to be unique, s can take all values except 2 and -2
Step-by-step explanation:

![\left[\begin{array}{ccc}2s&4\\2&s\end{array}\right] \left[\begin{array}{ccc}x_{1} \\x_{2} \end{array}\right] = \left[\begin{array}{ccc}-3 \\6 \end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D2s%264%5C%5C2%26s%5Cend%7Barray%7D%5Cright%5D%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Dx_%7B1%7D%20%5C%5Cx_%7B2%7D%20%5Cend%7Barray%7D%5Cright%5D%20%3D%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D-3%20%5C%5C6%20%5Cend%7Barray%7D%5Cright%5D)
For the system to have a unique solution, 

You divide 690 by 100 which is 6.9
Therefore, one 50cent coin is 6.9g