Two students, student 1 and student 2, did a hands-on mining exercise with cookies to compare the total cost of mining in two different land areas using different equipment. the table below shows the costs of land, equipment, mining, and reclamation for the two students.

Assume cost of equipment for student 2 is m.

We are given that:
Total mining cost for student 1 and student 2 is $40

For student 1:
We are given that:
Cost of land = $5
Cost of equipment = $2
Cost of mining and reclamation = $2 per minute
Time taken to mine = 5 minutes
Therefore,
Total mining cost for student 1= land + equipment
                                                  + cost of mining (time needed)
Total mining cost for student 1 = 2 + 5 + 2(5) = 7 + 10 = $17

This means that:
Total mining cost for student 2 = 40 - 17 = $23

For student 2:
We are given that:
Cost of land = $4
Cost of equipment = m
Cost of mining and reclamation = $2 per minute
Time taken to mine = 6 minutes
Total mining cost for student 2= $23
Therefore,
Total mining cost for student 2= land + equipment
                                                  + cost of mining (time needed)
23 = 4 + m + 2(6)
23 = 4 + m + 12
23 = 16 + m
m = 23 - 16
m = $7

Based on the above calculations, the correct choice would be:
c. $7