Question

evaluate the expression when a = -7 and x = 3. -x + 3a

Explanation:

Step1: Substitute given values

Substitute $x=3$, $a=-7$ into $-x+3a$:
$-3 + 3\times(-7)$

Step2: Calculate the multiplication

Compute $3\times(-7)$ first:
$-3 + (-21)$

Step3: Compute the final sum

Add the two terms together:
$-3 -21$

Answer:

$-24$