Y= consumption X= Disposable income

Question

Y X
5,000 10,000 A
8,000 20,000 B
Refer to info above. The slope of the line between points A and B is:
A) .3
B) 2.3
C) 3.3
D) indeterminate from this information.

How do you figure this out. What is the math to calculate this? Can any one help?