This is because these are similar rectangles, so the proportion of each side to the congruent side is the same. This means that to get from 7 to 28 u multiply by a scale factor of 4, and to get m you would multiply 4 by 4.
The answer is A because well 3x would not change and 17x would not change but 7 and 5 would change because they are not variable numbers So when u do the mah you would get 3x2+17x -2
