Example of when you would use a friendly numbers strategy to subtract

What term makes it inconsistent y=2x - 4

If sin(x) = 0 and cos(x) = 1, what is tan(x)?

Isabel graphed the following system of equations. 2x – y = 6 y = -3x + 4 she came up with the solution (2,-2). what were the 3 steps she did to get that solution? (make sure they are in the correct order)