Answer:
[tex]\$552[/tex]
Step-by-step explanation:
Let
x ----> the number of students that registered early
we know that
x=5
so
[tex]5(\$57-\$15)+(11-5)(\$57)[/tex]
The amount that the instructor collect from these 11 students is equal a 5 students registered early multiplied by $42 plus 6 students multiplied by $57
[tex]5(\$42)+(6)(\$57)[/tex]
[tex]\$210+\$342[/tex]
[tex]\$552[/tex]