The tower in Sydney revolves once every 7/6 hours

Since there are 24 hours in a day, then it revolves 24/(7/6)=20.571 revolutions in a day.

It is easy enough to tell how many times the tower in San Antonio revolves in a day since it is once every hour.

Subtract the two values to find the difference.

As for part 2, there are 360 degrees in a circle (assuming you are using degrees and not radians). The Sydney tower revolves 20.571 times in a day so that is 144 times in a week. That is 360*144=51,840 degrees in a week.

Now, can you find how many degrees the San Antonio tower turns in a week?. Then subtract the two to fins the difference.