174.97$ is the answer.
How I did it:
419.92 / 2.4 = 174.966 which rounds to 174.97$
Greetings!
An item at full price is 100%, or by using the percentage formula: 
If something is at 30% off, that means it is 70% of the original price (because minus the percentage from the 100%)
So by substituting the numbers into the percentage formula you end up with:
which is 0.7
So your answer would be D, 0.7!
Hope this helps!
1 represents the value of Point C on the number line.