I need steps on how to get to the answer. I'm confused

Could someone . i have tried to solve myself but my calculation is off

How do the kidneys affect homeostasis

Ateacher gives students four liquids commonly found in the kitchen - vinegar, apple juice, dish detergent, and milk - and ph indicator strips, which measure acidity. the teacher asks the students to put the liquids in order from most acidic to most basic. what type of investigation could the students conduct to determine the correct order for the liquids?