Twenty minus three equal seven fifties?

Lets do the numbers:

Two inches of snow
One bus ride to Dishman Pool
Five laps leading with my right arm and breathing every other stroke
Five laps leading with my left arm and breathing every other stroke
Six laps *with no rest at the deep end* leading with my right arm
Ninety seconds of rest between laps
One lap *with no rest at the deep end* leading with my left arm
Equals
One really good day in David's swimming progression