Which algebraic of an transformation on a coordinate grid does not preserve congruence

Idon’t understand this.. will someone ? will mark brainliest along with 20 points.

Kendra had twice as much money as kareem. kendra later spent $8 and kareem earned $6. by then,the two had the same amount of money. how much money did each have originally?

Will mark 50 show all what is the solution to the system of equations? use the substitution method and show your work. -5x+y= -3 -15 x+3y=7 explain what your answer in part (a) tells you about the association of the lines in this system.