## Intermediate Algebra (6th Edition)

$-3x-7.9$
We are given $(12x-1.7)-(15x+6.2)=12x-1.7-15x+6.2$. However, this is an incorrect use of the distributive property to distributive the negative sign to the second term. $(12x-1.7)-1\times(15x+6.2)=12x-1.7-15x-6.2=-3x-7.9$