4 The below table shows the contractor's monthly revenue for constructing a small house which will take 6 months to erect. The contractor prepares an invoice and submits it every two months and gets paid one month later. If the advance payment is 15% of total revenue, retention5%, and Mark-up 20%. TIME (Month) 1 2 3 5 6 Monthly Revenue 31 46 42 58 17 37 The cumulative income (in thousands of Riyals) to the contractor at the end of month number 5 is