I believe it is the 4th one
-3x + 2y = 14
You this way to solve it
Since AS is a height issued from A and the perpendicular bisector of [MP] at the same time (given), so the triangle AMP is an isosceles triangle of vertex A. Then, AM=AP
MS=SP ( AS bisects MP as stated in the given )
AS is a common side between triangles ASM and ASP
Therefore, triangles ASM and ASP are congruent (SSS)
Do what is in the parentheses then add