(-3,20) (3,0) (18,20) (13,18) is it a function

Whats the name of the vertical axis

8000 + 8800 + 8000 + 8 million + 80 trillion + another a katrillion equals

Two cyclists 84 miles apart start riding toward each other at the samen time. one cycles 2 times as fast as the other. if they meet 4 hours later what is the speed (in miles) of the faster cyclists