x intercept of 6 means (6,0) is on the line
y intercept of 0 means (0,0) is on the line
so the slope is (0-0)/(6-0) = 0
Answer: 0
Note: The question is actually bad; the line through the origin with slope zero is the X axis itself in which case it wouldn't be right to call the X intercept (just) (6,0).