Hi! For these types of problems we always result to going backwards. So, she now has 30 right? So, to reverse into the problem, we do the opposite of what it says. "She then bought five more" 30 - 5 = 25. Then it says she sold half of them. 25 x 2 = 50. If we recheck by going back, she sold half of them (50 / 2 = 25) and she bought five more (25 + 5 = 30).
