How is pH and hydronium concentration related?

Please help I am so confused

Write an equation of the line that passes through 9,2 and is parallel to the line y=5/3x+9

To decrease an amount by 16% what single multiplier would you use

Scenario: a rectangular plot of ground is 5 meters longer than it is wide. its area is 20,000 square meters. question: what equation will you find the dimensions? note: let w represent the width. options: w(w+5)=20,000 w^2=20,000+5 (w(w+5))/2=20,000 w+2(w+5)=20,000