Complex sentence: Six contestants enter each heat, with one quarter-finalist emerging from each of the four heats, and these four quarter-finalists compete for a semi-final place, so that over the first six weeks, six semi-finalists emerge.
Split into simpler sentences: Six contestants enter each heat, with one quarter-finalist emerging from each of the four heats. These four quarter-finalists compete for a semi-final place, so that over the first six weeks, six semi-finalists emerge.