Assume the extended demand function of good X is:

QDX = 1400 - 20 PX - 10 PY + 0.1 M

QDX = quantity demanded of good X

PX = Price of good X, M = Average consumer income

PY = Price of related good Y (related in consumption to good X)

M = Average consumer income

Assume that

PX= 50

PY = 50

M starts at 10,000 and increases to 20,000.What is the income elasticity of demand between these 2 values for M