How do you solve Qns 19 as attached?

\f19. Chng Company uses the weighted average method of inventory accounting (perpetual method) and follows the net method for all purchase discounts. The company started the year with 100 units in inventory, and an opening inventory balance of $3,000. The following table shows purchases in the first 3 months of the year. Invoice / FOB Credit Arrival Number Price Shipping Payment Shipping Terms Date of units per unit cost in Date Date (d/m) in S$ SS (d/m) (d/m) 1/1 Shipping 4/12,n/35 11/1 100 34 302 10/3 14/2 Destination 3/9,n/30 21/2 99 36 312 26/2 3/3 Destination 2/10,n/25 12/3 101 37 313 7/3 There are no purchase returns in the first quarter. The following table shows sales in the first three months of the year. Invoice / FOB Credit Arrival Number Price Shipping Payment Shipping Terms Date of units per unit cost in Date Date (d/m) in S$ S$ (d/m) (d/m) 23/1 Shipping 1/6,n/60 4/2 86 44 208 23/3 22/2 Destination 1/4,n/60 2/3 88 46 204 2/4 22/3 Shipping 1/5,n/30 1/4 89 45 210 20/4 On 6/2, 12 units are returned from the sales batch shipped on 23/1. Which of the following numbers is closest to the ending balance of inventory at 31/3? A. 5,457 B. 5,187 C. 5,098 D. 5,136