Answer:
The pressure upstream and downstream of a shock wave are related as

where,
= Specific Heat ratio of air
M = Mach number upstream
We know that 
Applying values we get

Similarly the temperature downstream is obtained by the relation
![\frac{T_{1}}{T_{o}}=\frac{[2\gamma M^{2}-(\gamma -1)][(\gamma -1)M^{2}+2]}{(\gamma +1)^{2}M^{2}}](https://tex.z-dn.net/?f=%5Cfrac%7BT_%7B1%7D%7D%7BT_%7Bo%7D%7D%3D%5Cfrac%7B%5B2%5Cgamma%20M%5E%7B2%7D-%28%5Cgamma%20-1%29%5D%5B%28%5Cgamma%20-1%29M%5E%7B2%7D%2B2%5D%7D%7B%28%5Cgamma%20%2B1%29%5E%7B2%7DM%5E%7B2%7D%7D)
Applying values we get
![\frac{T_{1}}{423}=\frac{[2\times 1.4\times 1.8^{2}-(1.4-1)][(1.4-1)1.8^{2}+2]}{(1.4+1)^{2}\times 1.8^{2}}\\\\\therefore \frac{T_{1}}{423}=1.53\\\\\therefore T_{1}=647.85K=374.85^{o}C](https://tex.z-dn.net/?f=%5Cfrac%7BT_%7B1%7D%7D%7B423%7D%3D%5Cfrac%7B%5B2%5Ctimes%201.4%5Ctimes%201.8%5E%7B2%7D-%281.4-1%29%5D%5B%281.4-1%291.8%5E%7B2%7D%2B2%5D%7D%7B%281.4%2B1%29%5E%7B2%7D%5Ctimes%201.8%5E%7B2%7D%7D%5C%5C%5C%5C%5Ctherefore%20%5Cfrac%7BT_%7B1%7D%7D%7B423%7D%3D1.53%5C%5C%5C%5C%5Ctherefore%20T_%7B1%7D%3D647.85K%3D374.85%5E%7Bo%7DC)
The Mach number downstream is obtained by the relation

Explanation:
We assume the T flip-flop changes state on the rising edge of the clock input.
The first stage is connected to the clock. The second stage clock is connected to the inverse of the Q output of the first stage, so that when the first stage Q makes a 1 to 0 transition, the second stage changes state.
Given:
Wall's inside temperature, 
Room air temperature, 
Solution:
To calculate percentage max relative humidity, we make use of steam table for saturated pressure of wall and air:
From steam table:
At
:

At
:

Now,


(RH)_{max} = 68.58%
Therefore, max Relative Humidity of the air before the occurrence of condensation in wall is 68.85%
I believe the answer is D: brazing
Hope this helps you have a good night