I know the answer is (a) but not sure how it gets there. Need help to better understand the approach.

3. During the month of June, the following transactions occurred for Boring Corp.: June 1 Collected $5,000 rent from a tenant for the month of June June 15 Sold $1,000,000 in goods (inventory cost $750,000) June 17 Paid operating expenses of $50,000 arising from expenses incurred in May June 18 Collected $18,000 from customers on account June 24 Purchased $800,000 in inventory; paid 50% in cash June 28 Incurred $75,000 operating expenses June 30 Received a utilities bill ($2,000) for the month of June Net income for the month of June is a) $178,000 b) $173,000 c) $128,000 d) $180,000