Calculate the circumference of the two semi circles, which equals a full circle. Then add the two sides of the track.
Circumference is pi x diameter = 3.14 x 22.8 = 71.592, so, you would need to add 71.592 + 49.2 + 49.2 = 169.992 meters, and that would be the length of one lap of the track.
When you multiply a number by 5 and then by 2 it is the same as multiplying by 10. multiplying by 10 means you add a zero to the end of the number so the digit in the ones column will be always be zero