y=mx+b
m=slope
b=y-intercept or where the graph crosses the y axis
from the equation y=-1/3x+2
slope=-1/3
y-intercept=2
so it is going downward from left to right
it also crosses the y axis at y=2
that rules out A and C
now the slope
slope=rise/run
given that slope=-1/3, rise=-1 and run=3
so for every 1 units it goes down, it goes 3 to the right
that would be D
the answer is D
