`2x - 3y + 4x + 5y`

`2x * text(-)3y + 4x * 5y`

`2x * text(-)3y * 4x * 5y`

`4a + 5b - 3a - 7b`

`p^2 - 2pq + p^2 + 3pq`

`text(-)2ab * b + 2a^2 * b - 2a*text(-)b^2`

`x^2 + 5x - 6x + 12 - 3x^2 + x`