Hello, I'll try to make this as easy to understand as possible, anyways, let's begin:
For this problem, we need a simple multiplication, we know that Olivia can walk 3 1/2 miles per hour, so we just multiply 3 1/2 by the number of hours that it tells us, but first, I like to convert the numbers, like this:
→ 3 1/2 can be turned into 7/2
→ 2 1/4 can be turned into 9/4
Then we multiply, like so:
7/2 * 9/4 = 63/8 = 7 7/8
So that means the answer is...
7 7/8.
Hope this helped! c: