First, draw horizontal line(in red below) at the lowest interface of Mercury P1 and connect along the line to P2 , then write the equations: going up (-), going down(+)
P1 = PB-γwater(h) >>>P1 = 207kPa-12.4kn/m3(5m)
P2= PA-γwater(h) + γHg (h) >>> P2= PA-8.4kn/m3(4m) + 133.02kn/m3(.4m)
P1= P2
207kPa-62kPa = PA-20.16kPa + 53.208kPa
Answer PA=111.95kPa