f(x) is a fancy way to say y
The equation says y=05, so x is ungiven based on what you have given us. Please check if there was more information written as usually its written as
Example: f(x)=3x+5
Answer:
$14.50 I think
cuz u add 6.50+ $8.00=$14.50
E=mc2 (5-2)x+99.03 with the addition of beans