c. \( 8 a-2 \geqslant 20 \)

To solve the inequality \( 8a - 2 \geqslant 20 \), start by isolating \( a \) on one side. First, add 2 to both sides to get \( 8a \geqslant 22 \). Then, divide both sides by 8, resulting in \( a \geqslant \frac{22}{8} \), which simplifies to \( a \geqslant \frac{11}{4} \) or \( a \geqslant 2.75 \). Keep in mind that inequalities can flip signs when multiplying or dividing by a negative number. When working with inequalities, a common mistake is misapplying the rules for negative numbers. Remember: only reverse the inequality sign when you multiply or divide by a negative! Another tip is to always check your final solution by plugging in numbers to ensure they satisfy the original inequality; this will help you catch errors.