Lenovo is the biggest PC maker in the world, but smartphones remain a challenge. The company's mobile arm announced a pre-tax loss of $292 million for the three months ending in June: Motorola phones shipped stood at 5.9 million, down just less than a third from last year. The company now plans to cut 10 percent of its non-manufacturing jobs (roughly 3,200 people), aiming to save around $650 million in the second half of 2015. It's also writing down $300 million in unsold phones. The company's total net profit dropped 51 percent year-on-year, down to $105 million.