If he walks 5days a week, then ride to and fro is equal to 10
If it cost him $2.75 each way to ride from home to work and back,
Then; The cost for ride in a week = 10 x $2.75 = $27.5
The amount save with the weekly pass = $27.5 - $20 = $7.50
Hence he saved $7.50 with the weekly pass