Markup = $4
b) markup as a percentage of cost is 33.3%
Step-by-step explanation:
Markup
markup = selling price - cost
= $13 - 9
... markup = $3
Markup as a Percentage of Cost
To find the percent markup, divide the markup by the reference value and multiply the ratio by 100%. The reference value for markup is usually cost price, but sometimes may be selling price.
... markup / cost × 100% = 3/9×100% = 33 1/3% ≈ 33.3%
7/18 - 5/18
First, we need to combine the denominators. Luckily for you, the denominators (18) are the same. If they weren't, it would be a whole other process to go through to get your answer. To combine our denominators, we connect them and subtract the numerators (7 and 5).

Second, subtract 7 - 5 to get 2. Your fraction should now be 2/18, but it can still be simplified down more. To do so, we need to find the greatest common factor (GCF) of the numerator (2) and the denominator (18). To figure this out, let's list the factors of both of them.
Factors of 2: 1, 2,
Factors of 18: 1, 2, 3, 6, 9, 18
Out of the factors listed, which are the common factors between the numerator and the denominator? 1 and 2 are the common factors, but since we are looking for the 'greatest' common factor, it would be 2 since it is the higher number. The GCF is 2.
Third, we can now divide both the numerator (2) and the denominator (18) by the GCF we just found which is 2.

Fourth, our last step is to combine the new numerator and denominator we recently found, which is 2 (the numerator) and 9 (the denominator). We will put them in fraction form and have our answer. Your simplified fraction should look like:

Answer in fraction form:

Answer in decimal form:
Answer:
X=7
Step-by-step explanation:
.........................
Answer:
The given expression is simplified as 
Step-by-step explanation:
Here,the given expression is (x+9)(x -9)
Using the ALGEBRAIC IDENTITY:

Now, here in the given expression (x + 9)(x -9)
Comparing it the left side of the identity,
we get a = x
and b = 9
The right side of the equation is 
Substituting the value of a and b, we get
⇒ 
= 
Hence, the given expression is simplified as 