Divide to see how many laps he can swim in one minute, then multiply that by 3 1/2 to see how many laps he can swim in 3 1/2 minutes.
\(\sf\dfrac{1}{3}\div\dfrac{1}{6}\)
You can multiply by the reciprocal.
\(\sf\dfrac{1}{3}\times\dfrac{6}{1}\)
\(\sf\dfrac{6}{3}\)
\(\sf 2\)
