The distance formula, d= √ (x2-x1)^2+(y2-y1)^2, is the key element in the proof of which of the following? a: the law of cosines b: cpctc c: the law of sines d: the triangle inequality theorem

The spanish club held a car wash to make money. the equation y=5x represents the amount of money y club members made for washing x cars. identify the constant of proportionality. then explain what it represents in this situation