So you subtract $22.89 from $54.73 to get a total of $31.84 and that’s how much the customer paid.
Convert 15% into a decimal. (0.15) Then multiply that by 550.
It is true because every term is the previous term multiplied by -2. So, -40 x -2 = 80, 80 x -2 = -160
The sum of two numbers will be zero when you have the same number and one is positive and one is negative. For example 1 + -1= 0