To find the total cost \( c \) of the oranges that Vicky bought, you can use the following information:
- Vicky bought \( 3 \frac{1}{2} \) pounds of oranges, which is equal to \( 3.5 \) pounds.
- Each pound costs \( $3.90 \).
The total cost can be calculated using the equation:
\[
c = \text{(cost per pound)} \times \text{(number of pounds)}
\]
So that translates into:
\[
c = 3.90 \times 3.5
\]
Now looking at the options given:
- 3.90/3.5 = c; Vicky paid $13.65. (This is incorrect since it divides instead of multiplying)
- c/3.90 = 3.5; Vicky paid $1.11. (This is incorrect as well)
- c/3.5 = 3.90; Vicky paid $13.65. (This is incorrect; it should actually be \( c = 3.5 \times 3.90 \))
- 3.90c = 3.5; Vicky paid $0.90. (This is incorrect because it doesn’t reflect the proper relationship)
None of the provided options correctly represents the equation for the total cost. However, if we were to rearrange what we already established, \( c = 3.90 \times 3.5 \), if written in terms of the given options, it would be:
c = 3.90 × 3.5, but again, this is not in your list.
If you must choose from the given options, you could clarify the numbers you're given, as the equations do not accurately represent the relationship needed to find the total cost of the oranges. If option 3 were written as \( c = 3.5 \times 3.90 \), it would be correct.
Given that none are appropriate, it seems like there might be a misalignment in the response options. If I had to pick the closest one, it would be:
c/3.5 = 3.90 (the rearranged version leads to the correct answer when re-calculating).
However, you will need to note the confusion and misrepresentation in the relationship.