What is income elasticity of demand?

Johnny Clutch just got a raise from \$900 per week to \$1100 per week. As a result, he decreases the amount of ramen noodles he buys from seven cartons a week to one carton a week. For Johnny, ramen noodles are:

Johnny Clutch just got a raise from \$950 per week to \$1,050 per week. As a result, he increases the number of concerts he attends by five percent. His demand for concerts is:

A twelve percent increase in consumer income has caused the quantity of orange juice demanded to increase from 24,000 to 26,000. The income elasticity of demand for orange juice is: