Answer
$12x-3x,$
simplifies to $9x$
Work Step by Step
"the product of three and a number" $\rightarrow 3x$
is subtracted from
"the product of 12 and a number" $\rightarrow 12x$
So, 3x is subtracted from 12x:$ \quad 12x-3x$
Combine like terms by combining the coefficients of the terms and keeping the same variable factor.
$12x-3x=\qquad 9x$
