Is this correct

3 1/8 • 4 = 28/8 • 4/1 = 100/8 divided by 4 = 25/2 = 12 1/2

It is incorrect because 3 1/8 times 4 is 12 1/2

28/8 or 3 1/2 times 4/1 or 4 is 12 1/2

100/8 divided by 4 is 3 1/8, and is not 12 1/2

I think you're suppose to multiply the wholes first so 3 x 4 is 12 so you're really dealing with ...

12 1/8 ... then multiply the bottom by the whole ...

12 x 8 is 96 now add the numerator and keep the denominator ...

97/8 ...

If I'm incorrect and your process is first then you are correct how you broke it down.