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1-9 Solving Equations by Adding Preview Warm Up California Standards Lesson Presentation Holt CA Course 1 1-9 Solving Equations by Adding Warm Up Solve each equation. 1. x + 7 = 22 x = 15 2. 18 + x = 105 x = 87 3. 16 = x + 9 x=7 4. 23 = x + 4 x = 19 Holt CA Course 1 1-9 Solving Equations by Adding California Standards AF1.1 Write and solve one-step linear equations in one variable. Holt CA Course 1 1-9 Solving Equations by Adding When John F. Kennedy became president of the United States, he was 43 years old. He was 8 years younger than Abraham Lincoln was when Lincoln became President. How old was Lincoln when he became president? Holt CA Course 1 1-9 Solving Equations by Adding Let a represent Abraham Lincoln’s age. Abraham Lincoln’s age a – 8 = John F. Kennedy’s age – 8 = 43 a – 8 = 43 +8 a +8 = 51 Abraham Lincoln was 51 years old when he became president. Holt CA Course 1 1-9 Solving Equations by Adding Additional Example 1A: Solving Equations by Adding Solve y – 23 = 39. Check your answer. y – 23 = 39 23 is subtracted from y. + 23 + 23 y Add 23 to both sides to undo the subtraction. = 62 Check y – 23 = 39 ? 62 – 23 = 39 ? Substitute 62 for y in the equation. 39 = 39 62 is the solution. Holt CA Course 1 1-9 Solving Equations by Adding Additional Example 1B: Solving Equations by Adding Solve 78 = s – 15. Check your answer. 78 = s – 15 + 15 + 15 93 = s 15 is subtracted from s. Add 15 to both sides to undo the subtraction. Check 78 = s – 15 ? 78 = 93 – 15 ? 78 = 78 Holt CA Course 1 Substitute 93 for s in the equation. 93 is the solution. 1-9 Solving Equations by Adding Additional Example 1C: Solving Equations by Adding Solve z – 3 = 12. Check your answer. z – 3 = 12 +3 +3 z = 15 3 is subtracted from z. Add 3 to both sides to undo the subtraction. Check z – 3 = 12 ? 15 – 3 = 12 ? 12 = 12 Holt CA Course 1 Substitute 15 for z in the equation. 15 is the solution. 1-9 Solving Equations by Adding Check It Out! Example 1A Solve a – 4 = 7. Check your answer. a–4=7 +4 +4 a = 11 4 is subtracted from a. Add 4 to both sides to undo the subtraction. Check a – 4 = 7 ? 11 – 4 = 7 ? 7 = 7 Holt CA Course 1 Substitute 11 for a in the equation. 11 is the solution. 1-9 Solving Equations by Adding Check It Out! Example 1B Solve 57 = c – 13. Check your answer. 57 = c – 13 + 13 + 13 70 = c 13 is subtracted from c. Add 13 to both sides to undo the subtraction. Check 57 = c – 13 ? 57 = 70 – 13 Substitute 70 for c in the equation. ? 57 = 57 Holt CA Course 1 70 is the solution. 1-9 Solving Equations by Adding Check It Out! Example 1C Solve g – 62 = 14. Check your answer. g – 62 = 14 + 62 + 62 g = 76 62 is subtracted from g. Add 62 to both sides to undo the subtraction. Check g – 62 = 14 ? 76 – 62 = 14 ? Substitute 76 for g in the equation. 14 = 14 76 is the solution. Holt CA Course 1 1-9 Solving Equations by Adding Lesson Quiz 1. x – 9 = 21 x = 30 2. 14 = x – 3 x = 17 3. x – 7 = 11 x = 18 4. 16 = x – 14 x = 30 5. x – 9 = 11 x = 20 6. Susan is taller than James. The difference in their height is 4 inches. James is 62 inches tall. How tall is Susan? 66 inches Holt CA Course 1