Suppose y varies directly with x. if y=-20 when x=2, find y when x=14 a)140 b)-1.4 c)-140 d)1.4

Suppose that the price p (in dollars) and the weekly sales x (in thousands of units) of a certain commodity satisfy the demand equation 4p cubedplusx squaredequals38 comma 400. determine the rate at which sales are changing at a time when xequals80, pequals20, and the price is falling at the rate of $.20 per week.

Why is causation so much more difficult to prove than correlation?

Will mark brainliest! ( explain the answer too, it can be one sentence)