Why does light refract (or bend), as shown in the illustration?

When will division i requirements change? requirements change every four years requirements change every year august 2016 requirements change every other year

If inflation is 6% and nominal gdp grew by 4%, then during the same period real gdp changed by a) -2% b) 2% c) 4% d) 5%

How do you work out 21.3-8= show your working. plz