A company that uses a perpetual inventory system made the following cash purchases and sales:
Jan 1: Purchased 100 units at $10 per unit
Feb 5: Purchased 60 units at $12 per unit.
March 16: Sold 40 Units for $16 per unit

Prepare general Journal entries to record the March 16 sale assuming a FIFO method is used.

Please help I can't figure it out.

What's so hard to figure out, first figure out what FIFO is, then relate that to the question. Reread the chapter dealing with the question in your text book. A quick Google search can provide a lot of information.