What is the ratio 15 to 40 in simplest form

If the ratio of sum of the first m and n terms of an ap is m2 : n2 , show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1).

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

What does independent variable and dependent variable mean in math?