Complex sentence: Jalan H.R. Rasuna Said was being developed in 1970's, which after completion along with Sudirman, and Gatot Subroto roads formed the "golden triangle" of Jakarta.
Split into simpler sentences: Jalan H.R. Rasuna Said was being developed in 1970's Road. After completion of the road along with Sudirman, and Gatot Subroto roads formed the "golden triangle" of Jakarta.