Here are reflection and rotation rules for coordinates. If you look at y=x and the one for 180 degrees you'll see the difference. It's hard to remember it but just study it and you'll be fine. :)
The answer would be y= 4x + 4 over 3
Because your slope would be 4/3 and the formula you needed was y=mx+b
The gross pay of the employee is the sum of his monthly salary and the amount he gained as commission from selling the units. That is,
gross pay = $400 + ($0.80)(1,425) = $1540
Thus, the employee's gross pay is equal to $1540.
6 and 100 can both be simplified if you divide them both by 2.
6 divided by 2 is 3.
100 divided by 2 is 50.
So the answer is 3/50. It cannot be simplified any further :)