f6數學題一問?10點

Since a,x,y,b are in arithmetic sequence , we havea + y = 2x ......(1)x + b = 2y ......(2)
1) Express x in terms of a and b (1)*2 + (2) :2a + 2y + x + b = 4x + 2y2a + b = 3xx = (2a + b) / 3
2) Express y in terms of a and b(1) + (2)*2 :a + y + 2x + 2b = 2x + 4ya + 2b = 3yy = (a + 2b) / 3