Solve for x: 3x + 5 = 20.

Solve for x: 3x + 5 = 20.

• A. 0
• B. 5
• C. 10
• D. 15

Answer: (B)

To solve a simple linear equation, you isolate the variable by undoing the operations on it. Subtract 5 from both sides to get 3x = 15. Then divide both sides by 3 to obtain x = 5. Check by substituting: 3(5) + 5 = 15 + 5 = 20, which matches the right side. Testing other possibilities: if x is 0, the left side is 5; if x is 10, it's 35; if x is 15, it's 50. Only x = 5 satisfies the equation.

To solve a simple linear equation, you isolate the variable by undoing the operations on it. Subtract 5 from both sides to get 3x = 15. Then divide both sides by 3 to obtain x = 5. Check by substituting: 3(5) + 5 = 15 + 5 = 20, which matches the right side. Testing other possibilities: if x is 0, the left side is 5; if x is 10, it's 35; if x is 15, it's 50. Only x = 5 satisfies the equation.