Question

If f footballs cost d dollars, then in terms of d and f how many dollars would 10 footballs cost? a) 10f dollars b) d⁄10 dollars c) 10d⁄f dollars d) d⁄10f dollars

Answer 1

Answer: Choice C

10d/f dollars

Reason

f = number of footballs that cost $d

d/f = cost of 1 football

For instance, f = 5 footballs cost d = $20. The unit cost, aka cost per football, is d/f = 20/5 = 4 dollars. One football costs $4 in this example.

But since we don't know the values of d or f, we cannot find the value of d/f.

Multiply it with 10 to find the cost of 10 footballs.

This is how we arrive at the answer 10d/f dollars