Last month, Inessa made 3 orders to replenish inventory. Her first order was for 400 units at $15.25; the second order was for 300 units for $16.50 and the last order was for 525 units at $17.80. The average price of the units is $16.40.

To find the average price of the units, you need to calculate the total cost of all units and divide by the total number of units. The total cost is (400 * $15.25) + (300 * $16.50) + (525 * $17.80) = $6,100 + $4,950 + $9,345 = $20,395. The total number of units is 400 + 300 + 525 = 1,225. The average price per unit is $20,395 / 1,225 = $16.65, not $16.40.