Final answer:
Christa needs to save $35 more to purchase a tablet that costs $70, as she has already saved $35. The total amount needed is subtracted by the amount already saved to determine the remaining amount required.
Step-by-step explanation:
Christa is working towards buying a new tablet that costs $70 including tax. She has already saved $35. To calculate how much more she needs to save, we simply subtract the amount she's already saved from the total cost of the tablet.
Total cost of the tablet = $70
Amount already saved = $35
Amount still needed = Total cost - Amount saved
Amount still needed = $70 - $35 = $35
So, Christa still needs to save $35.
The correct answer is B) $35.