Complex sentence: Through the 1930s, fortunes improved with new models, the Standard Nine and Standard Ten which addressed the low to mid range market and at the Motor Show of 1935 the new range of Flying Standards was announced with semi streamlined bodies.
Split into simpler sentences: Through the 1930s, fortunes improved with new models, the Standard Nine and Standard Ten addressed the low to mid range market. At the 1935 Motor Show the new range of Flying Standards was announced with (semi) streamlined bodies.