4/9 and 10/3 least common denominator?

The lines shown below are parallel. if the green line has a slope of -1, what is the slope of the red line?

To solve the system of equations below, grace isolated the variable y in the first equation and then substituted into the second equation. what was the resulting equation? 3y=12x x^2/4+y^2/9=1

True or false look at the picture pls : /