A Power Station Is on One Side of a River

Multiple Choice

A power station is on one side of a river that is 0.5 mile wide,and a factory is 6 miles downstream on the other side of the river.It costs $14 per foot to run overland power lines and $20 per foot to run underwater power lines.Estimate the value of x that minimizes the cost.The value of is the length of the overland piece of power line. ​

A) 2.56
B) 5.51
C) 3
D) 5.49
E) 0.87