1. \( 7(3 a+5) \)

To simplify \( 7(3a + 5) \), you’ll want to distribute the 7 to both terms in the parentheses. This means you multiply 7 by 3a to get \( 21a \), and then 7 by 5 to get \( 35 \). So, altogether, you get \( 21a + 35 \). Voila! Now that you've mastered distribution, did you know that this concept is foundational in algebra? Understanding distribution can make working with all sorts of expressions and equations a breeze. It’s like unlocking a secret code to simplifying math problems! Keep practicing, and soon, you'll be solving equations like a pro!