Solve 3x + 4 = 19. What is x?

Solve 3x + 4 = 19. What is x?

• A. x = 4
• B. x = 5
• C. x = 3
• D. x = 6

Answer: (B)

Isolating the variable to solve a linear equation. Start with 3x + 4 = 19. Undo the addition by subtracting 4 from both sides, giving 3x = 15. Undo the multiplication by dividing both sides by 3, yielding x = 5. So the solution is x = 5, since 3(5) + 4 = 19. Quick check: x = 4 gives 3(4) + 4 = 20, x = 3 gives 13, x = 6 gives 22, none of which equal 19.

Isolating the variable to solve a linear equation. Start with 3x + 4 = 19. Undo the addition by subtracting 4 from both sides, giving 3x = 15. Undo the multiplication by dividing both sides by 3, yielding x = 5. So the solution is x = 5, since 3(5) + 4 = 19. Quick check: x = 4 gives 3(4) + 4 = 20, x = 3 gives 13, x = 6 gives 22, none of which equal 19.