math.rationalize() made some mistakes

So I'm extremely happy with math.js, but I've had some problems with the following. Does anyone have a fix, I'm not sure what to do.

(a - b) + (a + 2b) was solved as a - b + a + 2 b and it should be 2a + b

2y + (3 - 4x) * 2 - 7x was solved as 2 y - 8 * x - 7 * x + 6 and it should be -15x + 2y + 6

2y + (3 + 4x) * 3 - 8x was solved as 2 y - 8 * x + 9 + 12 * x and it should be 4x + 2y + 9