First Part
The total cost is going to be equal to the cost of the studio for one day plus the cost of the technicians per day. This is because we are calculating the total value of one day.
Second Part
The cost of the studio for one day is $225, based on the information given in the statement.
Third Part
The inequality that models this is 210 ≤ 225 + 80 n ≤ 540.