How do you solve this equation 8d-1/3(6-9d)=42

Write two subtraction equations that are equivalent to 5 + 12 = 17.

An equation representing lyle’s hedge-trimming business is a = 12n - 300 where a is the amount of profit or loss in dollars and n is the number of hedges trimmed. how would the graph of lyle’s business change if the equation a = 10n - 300 represented his business? the graph would be flatter. the graph would be steeper. the graph would start closer to the origin. the graph would start lower on the y-axis.

Just tell me how to set up the equation.