1. Jonah's cell phone came with 64 GB of memory. He has used 15 GB. He then uses 5 MB of memory to record photos and videos from a trip. Use the addition expression 64 + (-15) + (-5) to find how much memory is left on his phone. 2. Stella walks down a flight of stairs to the basement. Then she walks back up the stairs and up another flight of stairs to the second floor of her house. Each flight of stairs represents a change of 12 feet in height. How far is Stella above the ground? . Find the sum. b. -121 + (-34) a. 64 + (-15) d. 109 + (-162) C. -86 + 92