Answer:
You could use a graphing calculator I just used Desmos. Origin is (0, 0). Rotate 90 degrees about the origin.
I used triangles
The rotated point would be at (1, 2)
ANSWER: the question mark = 1
I'm not 100% sure but what I remember it's this
Answer: y = 3/2x + 5
Step-by-step explanation:
Find the slope/gradient:

Plug in a point to the equation:

Solve for b:

New equation:
Range=highest number-lowest number
15-5=10
Range=10