The answer is D
Hope this hel
In triangle ABC,
AB^2 = CA^2+CB^2 (pyth. theorem)
AB^2 = 9^2 + 12^2
AB = √ 9^2+12^2
AB = √ 225
AB = 15
Simplify:
6x + 6 = 3x - 15
Now use all solutions
6(7) + 6 = 3(7) - 15
42 + 6 = 21 - 15
Nearly, you can tell it doesn't work.
6(-7) + 6 = 3(-7) - 15
-42 + 6 = -21 - 15
-36 = -36
So, -7 is x.
There are 6 balls to every box (a ratio of 6 to 1). Therefore, when there are 78 balls, there are 13 boxes.
