After winning the lottery, you decide to buy your own island. the island is located 1 km offshore from a straight portion of the mainland. there is currently no source of electricity on the island, so you want to run a cable from the mainland to the island. an electrical power substation is located 4 km from your island's nearest location to the shore. it costs $43 thousand per km to lay a cable in the water and $30 thousand per km to lay a cable over the land. what is the minimum cost to lay a cable to your island in thousands of dollars?