c) \( 20 a+8=-4+18 a \)

To solve the equation \( 20 a + 8 = -4 + 18 a \), start by getting all terms involving \( a \) on one side and constant terms on the other. Subtract \( 18 a \) from both sides, resulting in \( 20 a - 18 a + 8 = -4 \), which simplifies to \( 2 a + 8 = -4 \). Next, subtract \( 8 \) from both sides: \( 2 a = -12 \). Finally, divide both sides by \( 2 \) to find \( a = -6 \). To check your answer, substitute \( a = -6 \) back into the original equation: \( 20(-6) + 8 = -4 + 18(-6) \). This turns into \( -120 + 8 = -4 - 108 \), which simplifies to \( -112 = -112 \). Hooray! You’ve solved it correctly!