Multiple and divide signed numbers

Erin bought christmas cards for $2 each to send to her family and friends. which variable is the dependent variable?

Lizette is training for a marathon. at 7: 00 she left her house and ran until 8: 30, then she walked until 11: 30. she covered a total distance of 18 miles. her running speed was six miles per hour faster than her walking speed. find her running and walking speeds in miles per hour.

Which number line correctly shows 0.8 + 0.3?