please solve! the answer is 169 m.

Steam condensing on the outer surface of a thin-walled circular tube of 65mm diameter maintains a uniform surface temperature of 100C. Oil flows through the tube at an average velocity of 1m/s. Determine the length of the tube in order to increase oil temperature from 40 C to 60C. Physical properties of the oil are as follows: At50C:=12.4103kg/m.s=4.28105m2/sPr=143At100C:=9.3103kg/m.s(L=169m)