The radius of the front wheel of Brian's bike is 45cm. Brian goes for a cycle and travels 78.15km.
How many full revolutions did Brian's front wheel complete?

27639 full revolutions

Step-by-step explanation:

First, you need to find the circumference of the front wheel.  

The circumference formula is C = 2*π*radius

now plug in the radius.

2*π*45 is around 282.74333882cm

Next, convert the distance 78.15km into cm, because the circumference is in cm.

in a kilometer, there is 100000 centimeters. So just multiply 78.15 with 100000. You get 7815000.

Now divide 7815000 by 282.74333882 and you get 27639.90845059

disregard the 0.90845059 because that doesn't count as a full revolution, so the answer is 27639.