Water at a temperature of T∞=25 °C flows over one of the surfaces of a steel wall (AISI 1010) whose temperature is Ts,1=

[answerhappygod]

Water at a temperature of T∞=25 °C flows over one of the
surfaces of a steel wall (AISI 1010) whose temperature is Ts,1=40
°C. The wall is 0.35 m thick, and its other surface temperature is
Ts,2=100 °C. The thermal conductivities of steel AISI 1010 and
water are 61.7 W/(m⸱K) and 0.62 W/(m⸱K), respectively.
Problem: What is the temperature gradient in the
wall? The answer should be given using the unit of °C/m.
Note that the direction from the wall at Ts,2 to the wall
at Ts,1 is positive.