Please help, only b and c

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?

The experience c-0.25c can be used to find the cost of an item on sale for 25% off which expression beloit equivalent to c-0.25c

The random variable x is defined as the number marking the sector in which the arrow lands when the spinner in the diagram is spun once.