3k-1=7k+2
how do i solve this? and other problems like this?

To solve problems like this we have to have only one variable on LHS.

So
3k-1=7k+2    /-2 both side
3k-3=7k      / -3k both side
-3=4k        /:4 divide by 4 both siede

And know we can change sides.
k=

You do whatever you need to do in order to get  ' k ' all by itself on one side of the equation,and everything else on the other side.  BUT ... remember that whatever you do to one side of the equation, you must also do the same thing to the other side.

3k - 1  =  7k + 2

Here's one way to do it:

Subtract  2  from each side:    3k - 3  =  7k

Subtract  3k  from each side:      -3  =  4k

Divide each side by  4 :                - 3/4  =  k

If is congruent to,then m is the midpoint