X - 3y =17, -x - y=19 ???

The perimeter of a movie screen is 54 meters. the screen is 18 meters wide. how tall is it?

Astudent draws two parabolas on graph paper. both parabolas cross the x-axis at (–4, 0) and (6, 0). the y-intercept of the first parabola is (0, –12). the y-intercept of the second parabola is (0, –24). what is the positive difference between the a values for the two functions that describe the parabolas? write your answer as a decimal rounded to the nearest tenth

Is the number 128.439 a rational number