Explanation:
To find the distance travelled, you first have to find the circumference. After all, that is the part which actually touches the ground in the first place. The formula for the circumference is 2πr = C, where π=3.14, r is the radius (or half diameter). As such, we can plug in the values:
2*3.14*(26/2)=C -> 6.28*13=C -> 81.64 in = C