## Elementary Algebra

$-2.4$
First, we simplify the expression by combining like terms: $-7x+4y+6x-9y+x-y$ =$(-7x+6x+x)+(4y-9y-y)$ =$(-x+x)+(-5y-y)$ =$0+(-6y)$ =$-6y$ Now, we substitute $y=0.4$ into the expression: $-6y=-6(0.4)=-6\times\frac{4}{10}=-\frac{24}{10}=-2.4$