Can someone please help me and explain step by step how to calculate the May raw materials purchases in dollars? I can't seem to figure out the answer. Thank you so much!!

Rensing Ltd. estimates sales for the second quarter of 2017 will be as follows.

Month Units

April 2,500

May 2,490

June 2,330

The target ending inventory of finished products is as follows.

March 31 2,010

April 30 2,250

May 31 2,180

June 30 2,400

2 units of material are required for each unit of finished product. Production for July is estimated at 2,660 units to start building inventory for the fall sales period. Rensings policy is to have an inventory of raw materials at the end of each month equal to 50% of the following months production requirements. Raw materials are expected to cost $4 per unit throughout the period. Calculate the May raw materials purchases in dollars.