Question

(21) $5x - 4 = 2x + 11$
(22) $-2(x + 9) = -4x + 12$

Explanation:

For the equation \(5x - 4 = 2x + 11\)

Step1: Subtract \(2x\) from both sides

\(5x - 2x - 4 = 2x - 2x + 11\)
\(3x - 4 = 11\)

Step2: Add 4 to both sides

\(3x - 4 + 4 = 11 + 4\)
\(3x = 15\)

Step3: Divide both sides by 3

\(\frac{3x}{3}=\frac{15}{3}\)
\(x = 5\)

For the equation \(-2(x + 9)=-4x + 12\)

Step1: Distribute -2 on the left side

\(-2x - 18=-4x + 12\)

Step2: Add \(4x\) to both sides

\(-2x + 4x - 18=-4x + 4x + 12\)
\(2x - 18 = 12\)

Step3: Add 18 to both sides

\(2x - 18 + 18 = 12 + 18\)
\(2x = 30\)

Step4: Divide both sides by 2

\(\frac{2x}{2}=\frac{30}{2}\)
\(x = 15\)

Answer:

For \(5x - 4 = 2x + 11\), \(x = 5\); For \(-2(x + 9)=-4x + 12\), \(x = 15\)