Explain how you can find the opposite of the opposite of any number without using a number line

What is 20+(5 x 2/5 )+ 3 show your work

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.

The suare root of 9x plus 7 plus the square rot of 2x equall to 7