Final answer:
The simplest form of the expression is y - 4.1x.
Step-by-step explanation:
The simplest form of the expression (-12.7y - 3.1x) + 5.9y - (4.2y + x) is y - 4.1x.
To simplify the expression, we can combine like terms. Starting with the y terms, we have -12.7y + 5.9y - 4.2y, which simplifies to -11y. Next, looking at the x terms, we have -3.1x - x, which simplifies to -4.1x.
Combining these simplifications, we have (-11y) + (-4.1x), which can be written as y - 4.1x.