Answer:
C. 
Step-by-step explanation:
Given the two equations:

To find:
The correct option when value of y is substituted to 2nd equation using the 1st equation.
Solution:
First of all, let us learn about the substitution method.
Substitution method is the method to provide solutions to two variables when we have two equations and two variables.
In substitution method, we find the value of one variable in terms of the other variable and put this value in the other equation.
Now, the other equation becomes only single variable and then we solve for the variable's value.
Here, we have two equations and value of one varible is:

Let us put value of y in 2nd equation:

So, the correct answer is option C. 
Answer:
x = 5
Step-by-step explanation:
We need to find the value of x in this case.
For this, we need to consider that the triangles are similar. Now, we can find it as follows :

So, the value of x is equal to 5.
Answer:
-0.5
Step-by-step explanation:
5+8=13
13/2=6.5
6.5-7=-0.5
Let’s do 3x - 8 ≤ 23 first.
You need to rearrange this so that x is on its own.
+8 to both sides
3x ≤ 31
/3 on both sides
x ≤ 31/3
Then the second, -4x + 26 ≥ 6
-26 from both sides
-4x ≥ -20
/-4 on both sides
x ≥ 5
So x is greater than or equal to 5, which can also be written as 5 ≤ x
And for the first one, x is less than or equal to 31/3, which can still be written as x ≤ 31/3, so your final answer is:
5 ≤ x ≤ 31/3
Checkpoint A-> time being 1:00pm total miles driven being 120 and
checkpoint B-> time being 3:00pm and the total miles being 208
The distance between two checkpoint A and B is 208 - 120 = 88 miles
Now the time between the two checkpoints = 3.00 - 1.00 = 2 hours
We need to find car speed between the checkpoints
We know Distance = speed * time


Speed = 44 miles per hour