Please help ty!
Alex swims in a 400-m freestyle competition at an average speed of 1 1/3 m/s. If he increases his average speed to 1.6 m/s, how much less time will he take?

50 seconds

Recall the equation

d=rt

Distance = rates times time.

We have a single distance, 400m

We have two different rates 1 1/3 m/s and 1.6 m/s

Let's calculate the time for each rate

t = d/r

t = 400/(1 1/3) = 300 seconds

t = 400/1.6 = 250 seconds

By increasing his average speed, Alex will reduce his time by

300-250 = 50 seconds.