Evaluate 6•(4+)^2-3^2

Use the elimination method to find the solution to the system of equations. 2x - 3y = -9 -x + 3y = 6

What is perpendicular to y=-1/2x+11

The high temp today was 62°. when nighttime comes, the temp will drop 40°. by 4am the temp will drop an additional 40°. what is the temp at 4am?