Textbook problem 6 B.1

[Sharon Chu 3I]

The question is:
6B.1 The molar concentration of HCl in hydrochloric acid is reduced to 12% of its initial value by dilution. What is the difference in the pH values of the two solutions?
For my answer, I have pH=-log[H3O+] = -log(0.12)=0.92, but I have went through other answers in chem community and I see answers of the answer being pH=-log(0.88)

Which one is it and why?

[Nathan Morgan 2C]

Full disclosure, I haven't done this problem but from the looks of it, the question says reduced by 12% of its initial value. I am assuming the others may have gotten -log(0.88) from the 12%. 1-.12=0.88. This would then give you a value, but not the difference. Looking at the student solution manual, it looks like you are correct as you found the difference.