Final answer:
At 30 degrees west when it is 1:30 pm GMT on Saturday, it would be 11:30 am on the same day, Saturday.
Step-by-step explanation:
If it is 1:30 pm on Saturday according to Greenwich Mean Time (GMT), to find out the time and day at 30 degrees west, one must determine the time difference based on the longitude. Since every 15 degrees longitude represents a one-hour difference from GMT, 30 degrees would signify a difference of two hours. As you travel west, you subtract time, so at 30 degrees west, it would be two hours earlier than GMT.
Therefore, at 30 degrees west, the time would be 1:30 pm minus 2 hours, which results in 11:30 am. However, since there is no day change, it remains Saturday. So at 30 degrees west, when it is 1:30 pm GMT on Saturday, it is 11:30 am on Saturday.