By the time that tractor makes a complete resolution, it has covered the perimeter(circumference) of the circle.

How do we calculate the perimeter of the circle? 2πr !

You gave me an already cooked pie...

Haha, we are given pi to be \frac{22}{7}
The circle's diameter is 1.4m, so it's radius is \frac{140}{2}cm, which is 70cm.

(Note that I converted the units to cm to make our calculations easier.)

2πr therefore equals;

2 × \frac{22}{7} × 70cm
= 440cm

Thus, the wheel covers a distance of 440cm in one complete revolution.

In 100 revolutions therefore, the wheel covers a distance of;

(440 × 100)cm = 44000cm.

The value's unit in the question is in metres.

Therefore, the tractor's wheel covers a distance of 440metres in 100 complete revolutions.