maths.......................mAths

From the diagram, M is NOT the midpoint.

Let AM : MB = 1 : r
y-coordinate of M = (r * y-coordinate of A + 1 * y-coordinate of B) / (1 + r)
4 = (r * 3 + 1 * 7.5)/(1 + r)
4 + 4r = 3r + 7.5
r = 3.5

x-coordinate of M = (r * x-coordinate of A + 1 * x-coordinate of B) / (1 + r)
2c = (r * 8 + c) / (1 + r)
2c = (3.5*8 + c) / 4.5
9c = 28 + c
8c = 28
c = 3.5

2c=7+ 8
2c=15
c=7.5