First, find the increase in charge between the two station. That is:
$4.12-$4.00=$0.12
Then, divide the increase by the price charged by Gas Station X.
$0.12/$4.00=0.03
Lastly, since it is a decimal, transform it to percentage by multiplying 100%
0.03x100%=3%
Hope this is the brainliest answer.