Complex sentence: Keep Australia Beautiful was founded in 1969 and became popular in the 1980s with its "Do the right thing" campaign against littering and its Tidy Towns competition became well known in Australia due to it being a very competitive expression of civic pride.
Split into simpler sentences: Keep Australia Beautiful was founded in 1969 and became popular in the 1980s with its "Do the right thing" campaign against littering. Its Tidy Towns competition became well known in Australia due to it being a very competitive expression of civic pride.