Solve for x 51/34=3/x

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?

Table which ratio is equivalent to 3: 7? 6: 7 3: 21 24: 56 15: 30

What are two numbers that add up to -9 and multiply to -10 best answer gets branliest and 100 extra points