Charles bought 40 boxes of oranges for $258. there were 24 oranges in each box. he threw away 15 rotten oranges and sold the rest at 3 for $1. how much money did he make?

24 x 40 = 960 oranges
960 - 15 = 945
945 / 3 = 315 
so he made 315$

2) By definition of the midpoint point. If a point is in the middle of a segment, then the two resulting segment are equal. 
3) Obvious, the point K is on the line MJ.
6) From statement 5 and the property of fractions. 
8) SAS statement of congruent triangles (notice the two triangles share on common angle which is between the two proportional sides)
9) The two corresponding  sides are congruent. 
10) The constant of proportionality is 2. 
11) From statement 10.