Respuesta :
Answer:$9
Step-by-step explanation:
Let the additional amount be c
Total amount to spend on gift is $27
He had spent $18 so far
$18+c= $27
C= $27-$18
C=$9
[tex]\text{We could turn this scenario into an equation}\\\\27\geq18+c\\\\\text{You would solve for c to find how much more Sam can spend on gifts:}\\\\27\geq18+c\\\\\text{Subtract 18 from both sides:}\\\\9\geq\,c\\\\\text{This means that the additional amount Sam has is \$9}\\\\\boxed{\$9}[/tex]