1. Pre-Algebra Solve y + 5 = 13. Solving Equations by Adding or Subtracting Lesson 2-5 Method 1:Method 2: y + 5 = 13 Subtract 5 y + 5 – 5 = 13 – 5from each side. y = 8Simplify. y + 5 = 13 y = 8 Check: y + 5 = 13 8 + 5 13 Replace y with 8. 13 = 13 – 5 = – 5 Additional Examples

2. Pre-Algebra Larissa wants to increase the number of books in her collection to 327 books. She has 250 books now. Find the number of books she needs to buy. Solving Equations by Adding or Subtracting Lesson 2-5 target numberWordsplusis250number to buy =number to buy.xLet Equation 327+x250= Additional Examples

3. Pre-Algebra (continued) Solving Equations by Adding or Subtracting Lesson 2-5 327 = 250 + x Larissa needs to buy 77 more books. 327 = x + 250Use the Commutative Property of Addition. 327 – 250 = x + 250 – 250Subtract 250 from each side. 77 = x Simplify. Check: Is the answer reasonable? 250 plus the number of books bought should be a total collection of 327. 250 + 77 = 327 Additional Examples

4. Pre-Algebra Solve c – 23 = – 40. Solving Equations by Adding or Subtracting Lesson 2-5 c – 23 = – 40 c – 23 + 23 = – 40 + 23Add 23 to each side. c = –17Simplify. Additional Examples

5. Pre-Algebra Marcy’s CD player cost $115 less than her DVD player. Her CD player cost $78. How much did her DVD player cost? Solving Equations by Adding or Subtracting Lesson 2-5 78 = t – 115Write an equation. 78 + 115 = t – 115 + 115 Add 115 to each side. 193 = tSimplify. Marcy’s DVD player cost $193. cost of CD player$115cost of DVD playerWordsless thanwas t=cost of the DVD player.Let t 115 Equation78=– Additional Examples