please show excel function ex. (B4-C3)/2

FEDEX AND S&P 500 Excess return S&P Excess retum FedEx 500 Year 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 S&P total return -23.37% 26.38% 8.99% 3.00% 13.62% 3.53% -38.49% 23.45% 12.78% 0.00% 13.41% 29.60% 11.39% FedEx return 4.81% 24.91% 46.40% 5.33% 5.40% -17.61% -27.67% 31.13% 12.08% -9.66% 10.53% 57.58% 21.39% 1-year T-bill 2.17% 1.32% 1.26% 2.75% 4.38% 5.00% 3.34% 0.37% 0.47% 0.29% 0.12% 0.16% 0.13% Section b. Section c. Aggressive or definsive? Since Section d. Sharpe ratio Jensen's alpha