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At this site, there is a group of lessons related to this class of problems
- Find the slope of a straight line in a coordinate plane passing through two given points
- Equation for a straight line having a given slope and passing through a given point
- Solving problems related to the slope of a straight line
- Equation for a straight line in a coordinate plane passing through two given points
- Equation for a straight line parallel to a given line and passing through a given point
- Equation for a straight line perpendicular to a given line and passing through a given point (*)
- Advanced problems on finding equations for straight lines
- OVERVIEW of lessons related to the slope of a straight line
The most relevant to your current problem is the lesson marked (*) in the list.
So start from this lesson.
But if you want to learn the subject in all its aspects, you need to learn all these lessons.
Consider them as your textbook, handbook, tutorials and (free of charge) home teacher.
The method of solution is very simple, and this skill is of the basic level (as 2x2 = 4).
So, my goal is not to provide an answer to you --- my goal is to TEACH you to solve these elementary problems ON YOUR OWN.