In certain county, the number of charter schools is 4 less than twice the numbervof alternative schools. we know that there are 48 charter schools in the county. how many alternative schools are in the county?

1. Let's call the number of carter school: "x" and "y" the number of alternative school.  Then, you have that:

 - The number of charter schools is 4 less than twice the number of alternative schools.
 - There are 48 charter schools in the country.

 2. So, you have:

 x=2y-4  (i)

 x=48  (ii)

 3. Then, when you substitute x=48 into the equation (i), you obtain:

 x=2y-4
 48=2y-4

 4. Now, you must clear "y, as below:

 48+4=2y
 2y=52
 y=52/2
 y=26
 
 How many alternative schools are in the county?

 The answer is: There are 26 alternative schools.