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

We have that if we add 4 to the number of charter schools, we have twice the number of the alternative schools in the county. Hence, twice the alternative schools are 52. The half of this is 26. Hence, there are 26 alternative schools in the county. These steps correspond to solving the expression 48=4+2x.