#### Answer

If s is the number of students, the cost is:
$12s+150$

#### Work Step by Step

You can see in the table that the total cost includes 12 multiplied by some number. The number multiplied by 12 is the number of students in the first column. This tells us there is a \$12 charge per student.
You can also see in the table that there is an additional charge of \$150 no matter how many students are in the group. This base charge should be added to the per student fee.
Let s be the number of students. Replace the 20 with s in the total cost equation that is in the first row.
$(12\times20)+150\longrightarrow12s+150$
Looking at the total cost in rows 2 and 3, replacing the number of students with the variable s results in the same algebraic equation.