How do i do the algebraic rule

What is the length of bc ? enter your answer in the box. bc =

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

The graph of y=x3 is transformed as shown in the graph below. which equation represents the transformed function?