You have to distribute the 7 to x and 2 so :
7x+14=2x-1
Add one to both sides (inverse operations)
7x+14=2x-1
+1 +1
7x+15=2x
Cross Cancel by subtracting 7x from both sides
7x+15=2x
-7x -7x
15=-5x
Divide by -5
15/-5= -5/-5
X= -3
b must be equal to -6 for infinitely many solutions for system of equations
and 
<u>Solution:
</u>
Need to calculate value of b so that given system of equations have an infinite number of solutions

Let us bring the equations in same form for sake of simplicity in comparison

Now we have two equations

Let us first see what is requirement for system of equations have an infinite number of solutions
If
and
are two equation
then the given system of equation has no infinitely many solutions.
In our case,

As for infinitely many solutions 

Hence b must be equal to -6 for infinitely many solutions for system of equations
and
To determine the correct answer, you will need to find the ranges, means, medians, and mode of City B. You can compare the answers then to answer the question. Please see the attached picture for the necessary information.
The correct choice is the first statement about the mode for City B.