1. The user requests solutions for multiple exercises (3.1 to 3.5 and Review Exercise 3) from Unit 3, but no specific problems are provided. 2. To assist effectively, please provide the exact problems or equations from these exercises. 3. Once the problems are given, I will provide detailed step-by-step solutions using stacked fractions and clear explanations. 4. This approach ensures clarity and thorough understanding for each problem. Please share the specific problems to proceed.