Chapter 1 - Section 1.1 - Introduction to Algebra: Variables and Mathematical Models - Exercise Set - Page 11: 66

$2x+9=29$

"The sum of" tells us we are going to add the expressions that follow. "Twice a number" tells us we are going to multiply a number by 2 Let x be the number. "Is" tells us to write an equal sign, followed by the rest of the sentence, in this case the number 29.