What is the answer to number question

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?

Two years ago a man was six times as old as his daughter. in 18 years he will be twice as old as his daughter. determine their present ages.

This graph shows which inequality? a ≤ –3 a > –3 a ≥ –3 a < –3