Technically, none of the equations.
The equation you're looking for would be:
x²+(x+20)²=150²
Answer: (0,2) Explanation: You plug in the coordinates into the equation and find which points make the equation true. Plugging in (0,2) turns the equations into (2•0) + (3•2) = 6. Simplify it and you get 6 = 6 which is true.