6.30 The Texas Department of Transportation (TxDOT) is considering two designs for crash barriers along a reconstructed portion of I-10. Design 2B will cost $3 million to install and $135,000 per year to maintain. Design 4R will cost $3.7 million to install and $70,000 per year to maintain. Determine which design should be selected based on a rate of return analysis if TxDOT uses a MARR of 6% per year and a 20-year project period