Multiple 5/8 by the reciprocal of -3/8

Translate the word phrase into a math expression. 15 fewer than the product of 4 and a number. (pls immediately)

Agreeting card company can produce a box of cards for $7.50. if the initial investment by the company was $50,000, how many boxes of cards must be produced before the average cost per box falls to $10.50?

Acone with volume 1350 m³ is dilated by a scale factor of 1/3. what is the volume of the resulting cone? enter your answer in the box. m³