Please help ill give brainliest ive already failed this and had to re do it pleasee answer correctly

To isolate the term you should subtract 9 from each side.

Step-by-step explanation:

+ 9 = 4

 = -5

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.