-30 belongs to what family of real numbers ?

Based on what i know about mean, this doesn't add up.

Ben wants to play a carnival game that costs $2. in his pocket he has 5 red tickets worth 35 cents each, and 15 blue tickets worth 10 cents each. which of the following systems of inequalities correctly represents the constraints on the variables in this problem? let represent the red tickets and b represent the blue tickets.

Asquare parking lot has 6,400 square meters what is the length in meters