The demand for pencils by New York University students at the bookstore is given by the following equation, , where I is the average income of nyu students, in dollars per week, Q pencils is the quantity of pencils sold per week, and Pencils is the price per pencil, in dollars. Last week, the average income of New York Students students was $100 per week and the bookstore sold pencils for $1 each.

What was the price elasticity of demand last week?

Find what income elasticity of demand was last week.