In LIFO, while finding out the ending inventory where did 100 units x $24 come from? Also in COGS why is 700 units multiplied twice with different prices?

I need to follow the below question:

The Alpha company uses a periodic inventory system. The beginning balance of inventory and purchases made by the company during the month of July, 2020 are given below:

July 01: Beginning inventory, 625 units @ $32 per unit.

July 18: Inventory purchased, 775 units @ $36 per unit.

July 25: Inventory purchased, 580 units @ $39 per unit.

The Delta company sold 1,375 units during the month of July.

Required: Compute inventory on July 31, 2020 and cost of goods sold for the month of July using following inventory costing methods:

First in, first out (FIFO) method

Last in, first out (LIFO) method