Rewrite and evaluate the expression below by using the rule for subtracting integers

Step-by-step explanation:

B is correct.

you are taking 7 and "adding" negative to it.  

yeah and the opposite of cheating is studying ( you should try it some time)

step-by-step explanation:

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.