Which equation can be used to find mMN

How to choose the sign of the radical in the denominator of the formula for the distance from a point to a line.

Last month, a 770 g box of cereal was sold at a grocery store for $3.10. however, this month, the cereal manufacturer launched the same cereal in a 640 g box, which is being sold at $2.50. what is the percent change in the unit price?

Aramp rises 4 feet over a distance of 10 feet. what is the length of the ramp?