Transmigrated to the Seventies: The Fake Heiress Is a Research Genius

Shen Duyun was killed by a mutant in the apocalypse, then transmigrated to China in the 1970s, an era when you needed ration coupons to buy just about anything. The original owner was a lovesick fool with a generous streak, so Shen Duyun sent the scumbag and his cousin to join the original owner in the afterlife. She happened to repair a vehicle and caught the military's attention, then happened to see a computer and was begged by a research institute to join them.