Answer:
A biker has 216 miles distance from home to work.
Explanation:
Given:
Time required in usual speed = 4 hours.
Let usual speed be x
Hence distance can be calculated by multiplying time with speed we get.
Distance =
Also Given;
When the weather is bad, he travels 6 mph slower, and it takes him half an hour more
New speed will be 6 less than usual speed.
Hence Speed =

Also time required will be half an hour more than time required in usual speed.
Time = 4+0.5 = 4.5 hrs
Now distance can be calculated by multiplying time with speed we get.
Distance =

Substituting the values we get;

Hence Speed = 54 mph
Now Distance =

Hence Distance from home to work is 216 miles.