Hey there.
8/9d = 28; multiply both sides by 9.
8d = 252; divide both sides by 8.
d = 31.5
I hope this helps!
I'm guessing just to show that you did your work to get the answer.
Use the pythagoras theorem
And the answer will be 36.
A minute has 60 seconds, therefore we will deal with seconds now
And since we have it that the biker travels 5 feet every 0.5 seconds, lets multiply that by 2 to get the traveled distance per second to make it easier
5*2=10
Finally, multiply 10 feet by 60 seconds(1 minute)
= 600 feet
