Chapter 6 - Section 6.3 - Equations with Parentheses - Exercises - Page 242: 13

a=-5

Simplifying 2a + -1(5a + -7) = 22 Reorder the terms: 2a + -1(-7 + 5a) = 22 2a + (-7 * -1 + 5a * -1) = 22 2a + (7 + -5a) = 22 Reorder the terms: 7 + 2a + -5a = 22 Combine like terms: 2a + -5a = -3a 7 + -3a = 22 Solving 7 + -3a = 22 Solving for variable 'a'. Move all terms containing a to the left, all other terms to the right. Add '-7' to each side of the equation. 7 + -7 + -3a = 22 + -7 Combine like terms: 7 + -7 = 0 0 + -3a = 22 + -7 -3a = 22 + -7 Combine like terms: 22 + -7 = 15 -3a = 15 Divide each side by '-3'. a = -5 Simplifying a = -5