Answer:
Step-by-step explanation:
A common difference is the number you need to get from a chosen number on your left to get to the next number going right.
In the first sequence, you start with 10 on your left.
To get to the next number going right, you need to subtract 0.5 or add - 0.5
In any event, the common difference is -0,5
The second problem is a little harder. It does not follow the same sort of pattern that the first question does. This time you are multiplying or dividing.
200 * 1/2 = 100
100 * 1/2 = 50
50 * 1/2 = 25
25 * 1/2 = 13.5
So the common ratio is 1/2