How to find the slope of a perpendicular line?

It is the negative reciprocal to the slope of the line it is perpendicular to. For example, if the slope of that line was 3, the negative reciprocal would be -1/3, because if you multiplied them, -1/3 × 3/1, you'd get 3/3 which is 1. If the slope given was -4, the negative reciprocal would be 1/4, the negative reciprocal given of 1/2 would be -2, etc. I hope this helps! Let me know f I've just confused you :)

Cbecause they are equal so that means it is the same on both sides? ! hope this

The surface area would be 576 because you multiply all the numbers then multiply that number by 6