5. 20 = 10x - 6(2x + 5)

Explanation:

Step1: Expand the right - hand side

$20 = 10x-12x - 30$

Step2: Combine like terms

$20=(10x - 12x)-30$ $20=-2x - 30$

Step3: Add 30 to both sides

$20 + 30=-2x-30 + 30$ $50=-2x$

Step4: Solve for x

$x=\frac{50}{-2}$ $x=-25$

Answer:

$x = - 25$