Mark scored three times as many points as justin. write and algebraic expression to represent the number of points mark scored. explain the meaning of the variable

Quick translate "x is 12 units from 20" into an equation. what are the values of x being described? if you can answer any of my other questions that'd be great too

Find the solution to this system 2,1 1,-2 1,2 -1,2

Akindergarten class has 9 girls and 11 boys in class. what percent of the class are girlsit rain