Let’s start by setting up an equation to represent the distance each rollerblader travels:

Distance traveled by A = 6.8 m/s * t + 4.7 s * 6.8 m/s

Distance traveled by B = 11.4 m/s * t

The first term in the equation for A represents the distance A travels during the head start, and the second term represents the distance A travels after B starts racing.

We want to find the time it takes for B to catch up to A, which means that their distances traveled will be equal. So we can set the two equations equal to each other:

6.8 m/s * t + 4.7 s * 6.8 m/s = 11.4 m/s * t

Now we can solve for t:

6.8 m/s * t + 31.96 m = 11.4 m/s * t

31.96 m = 4.6 m/s * t

t = 6.96 s

So it will take B 6.96 seconds to catch up to A.