1) What is the rate of change from x = - 3 to x = 3?

What is the number 321,000,000 in scientific notation? also what is the number? ?

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

Need plz been trying to do it for a long time and still haven’t succeeded