Math Word Problem, please show steps?

Sara Shchneider commutes to her office in Redwood City, California, by train. When she walks to the train station, it takes her 40 minutes. When she rides her bike, it takes her 12 minutes. Her average walking speed is 7 mph less than her average biking speed. Find the distance from Sara’s house to the train station?

“When she walks to the train station, it takes her 40 minutes.”
40 minutes × 1 hour/60 minutes = ⅔ hour
⅔ hour × w miles/hour = (⅔)w miles

“When she rides her bike, it takes her 12 minutes.”
12 minutes × 1 hour/60 minutes = ⅕ hour
⅕ hour × b miles/hour = (⅕)b miles

(⅔)w = (⅕)b
10w = 3b

“Her average walking speed is 7 mph less than her average biking speed.”
w = b – 7
10(b-7) = 3b
b = 10 miles/hour

(⅕)b = 2 miles

My average commute to work ^_^